Abstract: A code to analyze the neutronic/thermo-hydraulic coupling effect was developed for the high performance light water reactor (HPLWR), which is a typical “three pass core” SCWR. Based on this code, a sensitivity study of different heat transfer correlations was performed on the neutronic/thermal-hydraulic coupling characteristics of HPLWR. Furthermore, the key parameters of HPLWR were investigated using the developed code. The results show that the developed code can be efficiently used to analyze the neutronic/thermo-hydraulic coupling behavior of HPLWR.