Abstract: The formation process for the TP304 stainless steel square pipe as applied to the AP1000 nuclear reactor is studied by means of such methods as deformation force calculation,finite element analysis,and technology testing,etc. As a result,a new formation process for the said pipe is developed,and the operation steps are:with the first pass,the hot-extruded blank pipe as sized is sink drawn,and with the second pass,the pipe is dawn with a mandrel,and finally it is turned into a square pipe as required. Moreover,all the parameters of the formation process are determined. The study shows that it is practical to employ the fixed-die drawing process to produce the TP304 stainless steel square pipe for nuclear power service,and that the finished product is in possession of material property homogeneity and high dimensional accuracy.