Abstract: In order to study the effect of different land use patterns on soil N mineralization, transportation, absorption and utilization of plant, and which lead to difference of soil nitrogen cycle, we selected four different land use patterns(i.e. poplar plantation, crop-poplar integrated system, meadow and cropland)in a coastal area of northern Jiangsu as the experimental sites. The variations of soil mineral N were determined by close-top incubation method. The soil net N mineralization rate, soil microbial biomass nitrogen(SMBN), water-soluble organic nitrogen(WSON)and soil physical and chemical properties were analyzed. The results showed that the net N mineralization rate decreased in order of poplar plantation, crop-poplar integrated system, cropland and meadow. Ammonium N was significantly positive correlated with microbial biomass nitrogen and total nitrogen, the nitrate N was significantly positive correlated with microbial biomass nitrogen, WSON and organic carbon, but the soil C/N was significantly negative correlated with ammonium N and total mineral nitrogen. The soil mineral nitrogen decreased with soil depth increasing. In 25-40 cm soil layers, the soil mineral nitrogen had significant difference with poplar plantation and crop-poplar integrated system. The results indicated that different land use patterns would affect soil net N mineralization rate, and the conversion of forest into cropland or crop-forest system could also alter the cycle rate of nitrogen significantly.