In order to explore the fitting effects of the artificial trial and error method and automatic optimization method based on SCE-UA algorithm in the mixed runoff area，the semi-humid and semi-arid Feng River Basin in Shaan'xi Province was selected to optimize the parameters using Xin'anjiang model . This paper discusses the applicability of the Xin'anjiang model based on the SCE-UA algorithm in the Feng River Basin, and analyzes the variation of the parameters especially. It is found that the parameters of SM and CS simulated by the two methods were large. The results show that the Xin'anjiang model based on SCE-UA algorithm has good applicability in Feng River Basin, and it is reasonable to compare the parameters of artificial test and error method and improve the optimization speed and simulation precision, which is not only simple but also efficient.