Recently, the Chinese Pulsar time measurement array research team, which is composed of scientific researchers from the National Astronomical Observatories of China of the Chinese Academy of Sciences and other institutions, has detected key evidence of the existence of Gravitational wave in the NaHz region using the Chinese Celestial Eye FAST, which indicates that the research on Gravitational wave in China has reached the leading level in synchronization with the international level. The relevant research results were published online in the Chinese astronomical academic journal "Astronomy and Astrophysical Research" on June 29, Beijing time. Nanohertz Gravitational wave is a kind of Gravitational wave, which is a Extremely low frequency disturbance in the universe. Its frequency is 10 to the negative 9th power Hz. Because of its extremely low frequency and long period of several years, the detection of the Gravitational wave with a wavelength of several light years is very challenging. Chang Jin, an academician of the CAS Member and director of the National Astronomical Observatories of China of the Chinese Academy of Sciences, pointed out that the Gravitational wave of the Nahertz is mainly an important "window" for human beings to observe the universe, and there will certainly be many important discoveries in physics. Using the Gravitational wave of Nahertz, researchers can study the supermassive objects in the universe, such as black holes, Supermassive black hole, the formation, evolution, merger of galaxies, and the early structure of the universe. These are major scientific issues in astrophysics. Using a large Radio telescope such as FAST, a Five-hundred-meter Aperture Spherical Telescope similar to our country, to conduct long-term time measurement and observation on a batch of Millisecond pulsar with extremely regular rotation is the only known detection method for the nanosecond Gravitational wave. Li Kejia, a researcher at the National Astronomical Observatory of the National Astronomical Observatories of China and a researcher at Peking University, said that in fact, the real Gravitational-wave observatory are those Pulsar. Researchers use large telescopes to read the signals of these Pulsar. They use these Pulsar as a very standard "clock". They read these "clock" signals to obtain time and judge how space is affected by Gravitational wave. In this research work, the Chinese Pulsar time measurement array research team used FAST to carry out long-term systematic monitoring of 57 Millisecond pulsar in the Milky Way, and formed these Millisecond pulsar into a galaxy scale detector to search for nanosecond Gravitational wave. The team took full advantage of FAST's high sensitivity, large number of Pulsar that can be monitored, and higher measurement accuracy, and based on self-developed software, analyzed and studied the data collected by FAST with a time span of three years and five months. On the premise that the false alarm rate is less than one half of a million, evidence of the existence of the NaHz Gravitational wave is found. Chang Jin, academician of the CAS Member and director of the National Astronomical Observatories of China of the Chinese Academy of Sciences, said that the evidence was the time of arrival of Pulsar, which was caused by the space-time ripples generated by the Gravitational wave of NaHz. A change in the angle of the Pulsar is an important basis for the existence of the NaHz Gravitational wave. They saw this change. Studying the Gravitational wave of the NaHz has profound significance for human exploration of the universe. Gravitational wave is a space-time ripple generated by the acceleration of a mass object disturbing the surrounding space-time. Its signal is extremely weak, but it is a direct means to detect the non luminous matter in the universe. Detecting Gravitational wave and opening a new window for Gravitational wave observation of the universe have long been pursued by astronomers, and it is also a goal for people