In order to reveal the effect law of different film mulching with nitrogen (N) fertilizer rate on the grain filling process of summer maize，the experiment of film mulching (plastic film，oxidationbiodegradable film，denoted as P and J) combined with urea (pure N 0kg/hm2，90kg/hm2，180kg/hm2 and 270kg/hm2，recorded as N0，N1，N2 and N3) was conducted to analyze the filling characteristic parameters and chlorophyll a/b content of summer maize. The results showed that within a certain range，with the increase of N application rate，the time to reach the maximum filling rate was delayed (maximum delay of 6.273d)，but the maximum filling rate and the average filling rate were increased，which were increased by 1.489mg/d and 1.062mg/d，respectively. Film mulching with N rate mainly prolonged the duration of fastincrease and slowincrease periods of filling，with 0.554~6.839d and 1.627~12.355d，respectively，and increased the average filling rate at fastincrease and slowincrease periods by 1.125mg/d and 0.285mg/d. P mainly extended duration of slightincrease，and improved the filling rate，while effect of J on extending the filling duration and improving the filling rate gradually appeared in fastincrease and slowincrease periods. Film mulching with N rate delayed the time of chlorophyll a/b to reach maximum (12~24d)，but prolonged the duration of photosynthetic activity，which was conducive to improve the quality of grain.