A field investigation was conducted at the Shenyang Experimental Station of Ecology, Chinese Academy of Sciences, in an aquic brown soil of Northeast China under three land use types (cropland, abandoned cropland, and woodland) in order to evaluate whether the vertical distribution and seasonal fluctuation for the number of total nematodes and trophic groups could reflect soil ecosystem differences and to determine the relationships between soil chemical properties and soil nematodes. The majority of soil nematodes were present in the 0-20 cm soil layers, and for these land use types plant parasites were the most abundant trophic group. In the abandoned cropland the numbers of plant parasites reached a peak on the August sampling date, whereas the cropland and woodland peaked on the October sampling date. Meanwhile, in all land use types the number of total nematodes, bacterivores, plant parasites, and omnivores-predators was negatively (P < 0.05, except for bacterivores in cropland, which was not significant) correlated with bulk density, and positively (P < 0.05, except for fungivores in abandoned cropland, which was not significant) correlated with total organic carbon and total nitrogen. A field investigation was conducted at the Shenyang Experimental Station of Ecology, Chinese Academy of Sciences, in an aquic brown soil of Northeast China under three land use types (cropland, abandoned cropland, and woodland) in order to evaluate whether the vertical distribution and seasonal fluctuation for the number of total nematodes and trophic groups could reflect soil ecosystem differences and to determine the relationships between soil chemical properties and soil nematodes. The majority of soil nematodes were present in the 0-20 cm soil layers, and for these land use types In the abandoned cropland the numbers of plant parasites reached a peak on the August sampling date, while the cropland and woodland peaked on the October sampling date. nematodes, bacterivores, plant parasites, and omnivores-predators were negatively (P <0.05, except for bacterivores in cropland, w hich was not significant) correlated with bulk density, and positively (P <0.05, except for fungivores in abandoned cropland, which was not significant) correlated with total organic carbon and total nitrogen.