Taken Alfalfa as an example, this study analyzed the impact of returning cultivated land to grassland in Zuli River basin. The entropy weight method was used to appraise the growth years for alfalfa. The results showed that the appropriate years for alfalfa in the northern of the basin is nine and sex for the southern of the basin. After the recommended planting years, the composite index significantly decreased. Then, the yield of alfalfa in Zuli river basin was expressed in map using multiple regression method.