162.5 m elevation appears a large number of cracks during construction period of Shankouyan arch dam，dam cracking will harm the structural safety.In this paper，the temperature field and stress field of Shankouyan arch dam under different working conditions are simulated using three-dimensional finite element simulation analysis method，the causes of cracks in 162.5 m elevation are analyzed.The results show that flood overtopping，high placing temperature，no water cooling，not taking effective warehouse insulation measures together leads to cracks.