On December 6, Luoyang Longmen Grottoes started the large-scale leakage water treatment and dangerous rock reinforcement and protection project of Fengxian Temple, which has started the large-scale protection project of Fengxian Temple again after 50 years since 1971. Fengxian Temple is located in the south of Longmen West Mountain in Luoyang, Henan Province. It is a group of cliff type group carvings with the largest scale and the most exquisite art in Longmen Grottoes. The inscription on the north side of the main Buddha lotus seat is called "dalushena statue niche". It is the largest niche in Longmen Grottoes and a representative work of sculpture art in the Tang Dynasty. It is about 34 meters wide from north to South and 39 meters deep from east to west. Eleven statues of one Buddha, two disciples, two Bodhisattvas, two heavenly kings and Hercules are carved in the niche. In addition to the cultural relic body and surrounding rock mass protected by Fengxian Temple, the protection project also includes the leigutai area. The staff will carry out emergency support and daily maintenance for the rock mass of leigutai South cave and the brick arch of the Ming Dynasty with safety and stability problems. The national level has been paying attention to the protection and research of grottoes. On December 7, the official website of the State Administration of cultural relics released the special plan for the protection and utilization of grotto temples during the 14th five year plan (hereinafter referred to as the plan). The Longmen Grottoes have been mentioned five times in the planning, and there are several small and medium-sized Grottoes in Henan Province. The plan calls for adhering to the cultural relics work policy of "protection first, rescue first, rational utilization and strengthening management", deeply understanding the new characteristics and requirements of the protection and utilization of grotto temples, and implementing the "grotto China" protection project. By 2022, important progress will be made in the innovation of grotto temple management system and mechanism, and major dangers of grotto temples will be completely eliminated, The security facilities of key grottoes and temples were fully covered, and the level of risk prevention and control and emergency response capacity were significantly improved. By 2025, the preservation of grottoes will be significantly improved, and the safety prevention ability will continue to improve. Leakage water and dangerous rocks have always been the main diseases threatening the safety of cultural relics in Longmen Grottoes. There is more rain in Henan this year. Fengxian Temple is the largest cliff statue niche excavated in Longmen Grottoes. The leakage water causes the dissolution of rock mass, and the corrosion re forms the accumulation of calcium carbonate on the surface of cave carvings, which destroys the integrity and artistic value of carvings. While the dangerous rock mass destroys cultural relics, it also seriously threatens the personal safety of tourists. On December 1, in front of Lushena Buddha in the south section of the west mountain of Longmen Grottoes, the construction unit built scaffolds in the designated safe construction area and passed the steel pipe up with bare hands. The project range is from the bottom of Fengxian Temple to the upper mountain, with a height of nearly 50m and a width of about 70m. In order not to affect visitors' visit, the construction is semi open, and the construction period is expected to be 270 days. The staff will also overcome the difficulties of winter construction and strive to complete the main project before next year's "Peony Culture Festival". The protection project makes full use of new technologies and methods. Longmen Grottoes Research Institute has established an expert group from Dunhuang Research Institute, China Cultural Heritage Research Institute, Fudan University and other units to guide the project, and carried out survey, design and scheme preparation by using ground penetrating radar detection, infrared imaging technology and 3D scanning surveying and mapping digital technology. For example, on the enclosure of the construction site, the survey map of cracks and water seepage diseases of Fengxian Temple displayed to the public marked the positions of cracks and water seepage points of the stone wall of Fengxian Temple in the form of 3D three-dimensional images. There are many cases in which Longmen Research Institute used new technology to protect the grotto temple. For example, in September this year, a one-to-one 3D printed Buddha head was placed on a residual statue of an equal standing Buddha by the staff of Longmen Research Institute. The two sections of the Buddha head and the residual statue are completely consistent. This has opened the road of "digital return" of scattered Longmen Grottoes, and it is also the first time that domestic scattered stone statue relics have realized "digital return". Compared with 50 years ago, today's protection engineering process uses new methods. Metakaolin and hydraulic lime are mainly used for the treatment of water leakage, which has a better protection effect on the Buddhist niche, while the old method of bolt support in the past is still used for the reinforcement of dangerous rock mass. Longmen Grottoes has made many attempts to protect and inherit the grotto temple. The return of cultural relics scattered overseas has various difficulties for various reasons. In the future, through the method of digital technology and the cooperation of interdisciplinary and domestic and foreign institutions, we will return the heritage information and cultural relics and statues. (outlook new era)