In order to reduce the effect of intensive rainfall on nitrate leaching in summer for greenhouse vegetable field in North Plain China, a three-year (2008—2010) field experiment was conducted in the suburbs of Beijing during the period of intensive rainfall season from July to September. Five different treatments were designed, including three nitrogen fertilizer levels (CK, no nitrogen fertilizer;N1, 380kg/hm and N2, 260kg/hm of nitrogen) in previously grown crop, and two other treatments with and without sweet corn as a catch crop based on the treatments of N1 and N2, denoted by N1C and N2C, respectively. The three-year field observed data was used to calibrate and validate the WHCNS (soil water heat carbon nitrogen simulator) model, and subsequently nitrate leaching, and water and nitrogen balance of different treatments were simulated. The results showed that evaporation and drainage were two main pathways of water consumption for the fallow treatments, while the main pathway of catch crop treatments was evapotranspiration and drainage. The amount of water drainage was in the order of CK>N1≈N2>N1C>N2C. Planting sweet corn can reduce nearly 42% of water drainage compared with without catch crop treatments. The water balance for fallow treatments was positive, and it was negative for the catch crop treatments, which indicated that the sweet corn consumed soil water stored in soil profile. The order of nitrate leaching rate of different treatments was N1>N2>CK>N1C>N2C, and the mass of nitrate leaching for catch crop treatments ranged from 1.3kg/hm to 50.9kg/hm, which was much lower compared with those of N1 and N2 treatments (59.2~273.6kg/hm), and even lower than that of the CK treatment (38.6~151.6kg/hm). The catch crop reduced 80% and 85% of nitrate leaching compared with treatments of N1 and N2, respectively. It can be concluded that using the deep-rooted sweet corn as a catch crop in summer can delay and control the nitrate leaching. Therefore, it can be used as an efficient method to reduce the risk of nitrate leaching for greenhouse vegetable field in the North China Plain.