Abstract: The problem of thermal fatigue cracks discovered in the pipes of mixing zones of cold and hot water in residual heat removal systems of pressurized water reactors is related to the safety of nuclear reactors. In this paper, a methodology for predicting the multiaxial fatigue life by using a reference curve fitted by uniaxial fatigue experimental data was adopted. For 304L stainless steel, which was the material of the pipes of mixing zones of cold and hot water in residual heat removal systems, the fatigue lives were predicted by using Dang Van, Matake and Fatemi-Socie criteria based on the fatigue experimental data collected from literature and the results of prediction were compared. The thermal fatigue lives of the pipe were computed by using Dang Van, Matake and Fatemi-Socie criteria based on a simplified 3-dimensional finite element model of the pipes of mixing zones of cold and hot water in residual heat removal systems, and the numerical results were compared with the experimental results. The results show that Fatemi-Socie criterion, which is based on strain (correlated by mean stress), is more suitable for the 304L stainless steel. Moreover, the predicted thermal fatigue life using Fatemi-Socie criterion is more reasonable than those using Dang Van and Matake criteria.