Crop model is an important tool to simulate crop growth and yield, which can provide a way to cope with the impacts of climate change and human activities, and achieve the target of saving water and increasing yield. Film mulching and watersaving irrigation are widely used in the arid regions of Northwest China. Therefore, the purpose was to modify the crop model AquaCrop based on compensating effect of soil temperature increase on effective air accumulation temperature and impacts of film mulching and canopy interception on rainfall infiltration, so as to make it more suitable for the simulation study of mulched seedmaize in arid areas. The modified model was calibrated and validated based on the experimental data of seedmaize in Shiyang River Basin in 2017. Then it was used to predict the variation of crop yield and water use efficiency (WUE) under the scenarios of future temperature increase and mulching ratio change. Results show that the modified AquaCrop can well predict the growth stages and canopy cover. The values of determination coefficient (R2) of the simulated and measured canopy covers were not less than 095, the values of root mean square error (RMSE) were between 3.9% and 10.1%, and the values of normalized root mean square error (NRMSE) were between 4.9% and 15.3%, indicating that the modified AquaCrop had a good simulation for canopy cover. The modified AquaCrop was validated for simulating soil water storage in 0~1m soil depth under different treatments with 0.60