Abstract: A field experiment with three nitrogen managements was conducted from 2005 to 2006 in Beijing Dongbeiwang experimental station to calibrate CERES-Maize model in DSSAT 4.0. Another two field experiments regarding irrigation amounts and sowing dates were conducted in 2006 to validate CERES-Maize model. After model validation, normal maize production and photothermal potential productivity were simulated by using 30 years weather data from 10 weather stations in the North China Plain (NCP). The results show that average photothermal potential productivity is in the range of 13.53 to 22.56 t/hm2 in the NCP under the condition of one crop one year. Maize photothermal potential yield increased by delaying sowing date in range of the end of April to middle of June, and the main driving factor of this trend was average daily radiation during grain filling stage in the north NCP, while that in the south and middle NCP was on daily temperature condition. There was a delaying trend about optimized sowing dates from north to south in the NCP. In the north NCP, optimized sowing date was around early May in Huailai region (40.23 oN Latitude), while it was late May in region of Beijing, Tianjin and Laoting (39.05oN～39.48oN Latitude). And in the south and middle NCP ( 35.34 oN～38.20 oN Latitude), maize sowed in early June could reach the maximum yield.