The research was based on a developed model for farmland water-salt transport and crop growth (LAWSTAC). In order to explore the response of farmland water and salt transport and crop growth to deficient drip irrigation and test the applicability of LAWSTAC model in the northwest arid region, field experiment was carried out in the Wuwei Experimental Station for Efficient Water Use in Agriculture, Ministry of Agriculture and Rural Affairs in 2018. Three treatments were considered in the experiment, including three irrigation levels, i.e., 100%, 70% and 40% of full irrigation (i.e., W100, W70 and W40), respectively. The results showed that salinity in shallow (0~20cm) soils was reduced after the irrigation during the seedling period of seed-maize production. For the whole growth period, the greater the irrigation amount was, the more obvious the phenomenon of desalination in upper layer and salt accumulation in deeper layer was. Larger irrigation generally resulted in higher plant leaf area index (LAI) and higher final above-ground biomass of the seed-maize under the three irrigation levels. The LAWSTAC model can well simulate the farmland water-salt transport and the growth of seed-maize. The values of determination coefficient (R2) of the simulated and measured LAI were 0.99，and the values of root mean square error (RMSE) were between 0.20cm2/cm2 and 0.87cm2/cm2. The values of R2 of the simulated and measured aboveground biomass were 0.99, and the values of RMSE were between 1.62t/hm2 and 3.57t/hm2. It was demonstrated that the LAWSTAC model can accurately simulate the dynamic changes of LAI and aboveground biomass of seed-maize. LAWSTAC model was validated for simulating soil water storage in 0~80cm soil layer under different treatments with 0.41