Abstract: This paper points out that the initial state variables of Xin'anjiang Model, which have influence on the calculation results, include initial soil water content W0, initial inter flow QI0 and initial underground flow QG0, where W0 consists of upper water content WU0,lower water content WL0 and deep water content WD0. Taking the flood of Caopu station in Buji River Basin as an example,the values of WU0、WL0、WD0、QI0 and QG0 are set respectively for flood simulating. The results show that WU0、WL0、WD0、QI0 and QG0 are very sensitive and have significant influence on the simulating results. The influence of WU0、WL0、WD0 on flood peak and flood volume is significant,and the degree depends on the change scope of WU0、WL0、WD0. The larger scope of the change the greater the influence. However, QI0 and QG0 have a systematic and co-directional influence on the calcula-tion results,that is, with the increase or decrease of QI0 and QG0, the calculation results show a systematic in-crease or decrease.