According to the connotation of rural water conservancy modernization in China, an evaluation index system with 2 layers and 6 classes, in total 26 indices, is established. The initial values of evaluation indices are obtained through investigation, and then each index is standardized and its threshold is determined. A mathematical model is established. The initial weight is obtained by using the analytic hierarchy process (AHP), and further the combination weight is determined. Finally, a case study of Boxing County in Hebei Province is investigated using the comprehensive evaluation method of combination weight. The evaluation value is 0.743. The results show that the rural water conservancy modernization in Boxing County is at the medium level of modernization, and it is consistent with its actual development situation.