With the increasing requirements of environmental protection in China,a new green and environmental protection method is urgently needed to solve the problem of removing the old paint layer from steel structures. In this paper,nanosecond laser is used to study the paint removal,and the influence of different laser process parameters(power,frequency,scanning speed and scanning times) on the weight percentage of Fe element and surface roughness is explored. The results show that the change of the scanning speed of the galvanometer has the most significant influence on the weight percentage of Fe and the surface roughness within the preset parameter rang. And then,the better paint removal parameters is determined:power 70 W,galvanometer scanning speed 1100mm/s,laser frequency 80 kHz,scanning time twice,and the processing effect of roughness between 50～100μmwithout paint residue is obtained.