Pipes with square cross sections are used as structural elements in buildings and automotive industries. These pipes can be produced from the round pipes by the reshaping process. In actual production, the design of process variables such as diameter of round pipe, profile of rolls and number of necessary stands are carried out experimentally.In this paper, a computer aided simulation code has been developed based on the 2-D elasticplastic finite difference method. The shear deformation is considered in the analysis of the reshaping process. By using this program, the effect of various parameters such as initial round pipe diameter and mechanical properties of metal on product dimension and quality can be investigated. Moreover, design of reshaping process including the peripheral shrinkage, the necessary number of stands, the radius of rolls and the height of pipe at each stand, can be performed.This simulation can reduce trial and errors and costs and help to manufacture the square pipes with high dimensional accuracy and good quality. Comparisons between the obtained results and experimental results are made and the applicability of obtained results is confirmed.