Abstract: Based on the research result relating to the mechanism for development of and causes for residual stress, the influence by residual stress on the manufacture process of ERW linepipe is analyzed by means of plastic deformation analysis method and relative statistic method. Accordingly control actions are proposed in order to reduce the residual stress as developed in the manufacturing process of ERW linepipe. It is regarded that sizing and hydrostatic testing are both two critical processes to prevent the pre-welding asymmetric deformation and the influence of resilient stress of the steel strip.