In order to more deeply and accurately study the real stress situation of diversion tunnel near arch dam abutment so as to ensure the safe operation of diversion tunnel in construction period, this paper analyzed the impact of dam on the diversion tunnel near dam abutment .It used Ansys finite element analysis to establish the whole finite element model of arch dam and diversion tunnel,and analyzed the additional stress of arch dam produced by arch dam in the conditions of own weight and own weight plus hydrostatic situation,which can provide the basis for the reinforcement of tunnel.The results show that the additional stress of diversion tunnel generated near arch dam abutment can not be ignored. The rock body grouting of dam abutment has certain effect on reducing the additional stress.The results can provide reference for the design and construction of diversion tunnel near arch dam abutment.