An investigation of soil fauna was carried out in swamps,willowshrub meadows,cultivated lands and secondary forestlands in three different tundras in Da Xinganling Mountains in J une,August and October,2003.A total of 39 225 individuals of soil animals,belonging to 4 phyla,8 classes and 24 orders were collected and sorted into macro,meso/micro and hygric fauna.Analysis of the populations of the three groups of soil animals did not show any consistent positive relationship between them in community.The investigation of horizontal distribution of the animals indicated a decreasing trend of the numbers of individuals and groups of meso/micro soil fauna from island tundra to the continuous tundra,which is similar to the general law of the distribution of soil fauna (that is,the number of soil animals gradually decreased from low latitudes to high latitudes),and a reverse trend in terms of the numbers of individuals and groups and biomass of macrofauna and the population of hygrocole as well.Their inconsistent and even reversed distribution rules revealed complexity of the relationship between locality and region of ecosystem.The numbers of individuals and groups of soil fauna were significantly and positively related to contents of organic matter and total nitrogen in the soil.The investigation of vertical distribution of soil fauna indicated that the individuals and groups of meso/microfauna were mainly distributed in the surface soil layer,but those of macrofauna peaked in the sublayer.The analysis of soil fauna diversity indicated that the diversity index of meso/microfauna declined from the island tundra to the continuous tundra,whereas the diversity index of macrofauna did not show any obvious law of variation between tundras.