In order to reveal the effects of different nitrogen application levels on maize grain filling process under water andfertilizer integration conditions，field trials were conducted in Ningxia Farming Pingjibao Farm from 2017 tO₂018.Thetest variety was“Tianci19”at0，90，180，270，360 and 450 kg/hm²nitrogen levels(represented byN0，N1，N2，N3，N4 and N5 respectively).Based on Richards equation，the model of grain filling process under different nitrogentreatments fertilization with drip irrigation and was constructed and verified，and the filling parameters wereanalyzed.Theresults showed that the filling rules of maize grain at different nitrogen levels were consistent with Richardscurve，the modelevaluation index RMSE was 1.03 g/kg，and the standardized root mean square error(n -RMSE)was5.56%.The grain -filling rate increased first and thendecreased，and the grain -filling process was divided into threestages:gradual increasingstage，rapid increasing stage and slow increasingstage.Nitrogen application significantly increased dry matter accumulationingrains，mainly due to the extension of grout duration and the increase of groutrate.Nitrogen application of 270 kg/hm² had a significant effect on the number of days of grain-filling during the accelerated growthperiod，which resulting in 64%of contribution rate for the rapid growth period to the final dry matter accumulation ofgrains，and maintaining a high activity of grain-filling in the laterperiod.In thispaper，the grain filling process model based on Richards equation will accuratelypredict the grain filling characteristics during the filling period of drip irrigationmaize.