The carbon fiber subway train developed by CRRC Qingdao Sifang Locomotive and Rolling Stock Co., Ltd. and Qingdao Metro Group for Qingdao Metro Line 1 has been officially released in Qingdao. This is the world's first carbon fiber subway train for commercial operation. At present, the carbon fiber subway train has completed the factory type test. According to the plan, a passenger demonstration operation will be launched on Qingdao Metro Line 1 within this year. Traditional subway vehicles mainly use metal materials such as steel and aluminum alloys, which are constrained by material characteristics and face weight reduction bottlenecks. Carbon fiber has advantages such as lightweight, high strength, fatigue resistance, and corrosion resistance. Its strength is more than 5 times that of steel, but its weight is less than 1/4 of steel. It is an excellent material for lightweight rail vehicles. The main load-bearing structures of the carbon fiber subway train, such as the body and bogie frame, are made of carbon fiber composite materials, which have technological advantages such as lighter, more energy-efficient, higher strength, stronger environmental adaptability, and lower operating and maintenance costs throughout the entire life cycle. (Lai Xin She)