Abstract: For the conservative treatment of sporadic seismic load, a lot of dampers and drop frames were used in the nuclear power plant piping system, which lead to the high cost for the manufactory, installation, in-service inspection and repair. According to the research scheme for integrity evaluation of pipe system under seismic effect, this paper completed the ultimate anti-seismic capacity test of nuclear pipes. Through the comparative study of the test and calculation results and the current specification, the safety margin of current pipeline design standard is clarified. A recommend value of damping ratio and stress evaluation of nuclear piping system is given.