The purpose of this study was to investigate the effects of different water stress gradients and biochar application on the growth and soil environment of silage maize in Yinda irrigation district of Gansu Province. A two-factor randomized block design was adopted. Three biochar application levels（B0：0 t/hm² ，B1：15 t/hm² ，B2：30 t/hm² ）and three water gradients（W1：80%-95% of field water capacity，full irrigation，W2：65%-80% of field water capacity，mild water stress，W3：50%-65% of field water capacity，moderate water stress）were set up. The study was conducted from multiple perspectives such as growth dynamics and yield of silage maize，and soil enzyme activity，in order to clarify the specific effects of water stress and biochar application on the growth and yield of silage maize，soil water content and soil environment. The results showed that soil water content under W1B1 treatment was significantly higher than W1B0 and W1B2 under full irrigation of W1（P＜0.05）. Under mild water stress W2，soil water content under W2B1 treatment was the highest （P＜0.05）. Under moderate water stress W3，biochar significantly improved soil water content，especially under W3B1 and W3B2 treatments（P＜0.05）. Under the same water stress conditions，the application of biochar significantly increased the plant height and stem diameter of silage maize（P＜0.05），in which W2B1 treatment showed the best performance，and the plant height and stem diameter reached the maximum value. The yield of fresh grass，hay and grain of silage corn reached the maximum under W2B1 treatment，which was consistent with the yield components such as ear size and ear length（P＜0.05）. Under moderate W2 water stress，water production efficiency and irrigation water use efficiency were the highest（P＜0.05）. Soil enzyme activity reached the highest level under W2B1 treatment（P＜0.05）. In summary，it was recommended to maintain 65%-80%（W2）of the soil water content in the field during the whole growth period，and apply 15 t/hm² （B1） level of biochar as the optimal water-saving，high-efficiency and stable yield treatment. This recommendation was based on the remarkable improvement of the growth，yield and soil enzyme activity of silage maize under this treatment combination， which could provide a scientific basis and practical guidance for the planting of silage maize in Yinda irrigation district.