Segregation and liberation occur easily in high nitrogen stainless steels, which can result in the formation of pores and the discarding of the steels. So it is very important to investigate the segregation and liberation theory during the solidification process of high nitrogen stainless steels. In the manuscript, the pouring and solidification progress of high nitrogen steels ingots were simulated through Pro Engineer and PROCAST software. The dynamic variation of temperature field and pressure field were obtained. With the results of PROCAST, the macrosegregation of 20kg weight ingot and 1.7 tons weight ingot were predicted using mathematical model of zone segregation. The predicted results show that 20kg weight ingot has no obvious macrosegregation and 1.7 tons weight ingot has obvious macrosegregation, which is consistent with measuring results. It shows that the accuracy of simulation and calculation to segregation of high nitrogen steels solidification process based on PROCAST software is high.