A 3-year field experiment was conducted at China Agricultural University Field Station in Beijing suburb to study characteristics of nitrate leaching in vegetable fields under different applied N-fertilizer amount treatments. Results showed that nitrate concentrate under traditional N-fertilizer applied treatment was significantly higher than those of two improved N-fertilizer applied treatments; Average nitrate leaching amount during Cauliflower, Amaranth and Spinach growth under two improved applied N-fertilizer amount treatments were of 19%, 18%, 9% and 13%, 34%, 21% of those of traditional treatment; In the whole experiment period and in the fallow period, annual average cumulative nitrate leaching amount under traditional N-fertilizer treatment constituted of 1/2 and 20% of total N-fertilizer applied amount, respectively, contrasting to less than 1/4, 6% under two improved N-fertilizer treatments, respectively. No significant influence on vegetable yields was found between different treatments.