This research work illustrates the results of studying the biodiversity of soil invertebrates of two biotopes (birch and mixed forest) in the foothills of the beyond Ili Alatau and their seasonal dynamics. Among the biomass of animals in the soil, earthworms are the largest component. During the study, 11 species of earthworms belonging to the family Lumbricidae were registered. In addition, the features of the process of their seasonal migration were described in the studied biotopes. As a result, it was found that earthworms are distributed more evenly in mixed forests than in birch forests. One of the main reasons for the migration of lumbricides is to ensure the passage of vegetation periods in favorable conditions. The maximum level of their activity is observed with a positive ratio of temperature and humidity in the habitat. The seasonal ratio of the number of soil invertebrates varies depending on the season. In the spring, soil warming, the loss of plant residues leads to the subsidence of saprophages in the deep layers of the soil.