Abstract: Due to shortage of agricultural water resources, extensive irrigation methods and unreasonable allocation of water and fertilizer, water and soil resources in middle reaches of Heihe River are seriously wasted．To save water and soil resources and improve local production level, technology of drip irrigation under film was adopted based on combination of field experiments and theoretical analysis．This technology could adjust deficit in middle reaches of Heihe River（Minle County Yimin Irrigation Station, Zhangye City）where water resources were scarce from May to September 2021, dry matter accumulation of soybean and its effect on yield under coupling of water and nitrogen under mulch drip irrigation were mainly studied．Results showed that under a certain amount of irrigation, appropriate amount of nitrogen fertilizer could promote dry matter accumulation of soybean, but excessive nitrogen would lead to a downward trend in accumulation process of dry matter of soybean．N₂W₂ treatment was a water nitrogen coupling mode to achieve better soybean yield．Compared with CK（no nitrogen application）, N₁, N₃（high nitrogen application）treatment significantly increased soybean yield by 39.94%, 13.11%, 20.73%．