College of Life Sciences， Inner Mongolia University，Hohhot ，China

The effects of large-scale continuous coal mining activities on soil microenvironment around mining pits in the eastern steppe area were studied to explore the disturbance mechanism of mining spatio-temporal sequence gradient on ecological system， and provided basic data for solving the ecological environment problems in the mining areas.In this thesis， natural grassland outside Baorixile open-pit coal mine area were taken as the research object， with the distance from the mining pit as disturbance intensity gradient， and the the mining advance time as the disturbance time gradient and sample point C3 was used as comparison.The spatiotemporal heterogeneity of soil biological activity in the grassland ecosystem under the disturbance of open-pit coal mining was explored by measuring the number of soil microorganisms， enzyme activities， and soil physicochemical properties in different soil layers.The results show that： ①Along with the increase of disturbance intensity， the number of bacteria， fungi and actinomyces in soil， activities of invertase， urease， phosphatase and catalase， as well as soil water content and total nitrogen content decreases， while the soil ammonium nitrogen and available phosphorus content increases.② With the extension of the interference time， the effects of mining disturbances on actinomycetes， invertase， urease，phosphatase， catalase， soil water content， ammonium nitrogen， available phosphorus and total nitrogen are enhanced， while it has less effect on the quantity of bacteria and fungi.③Under the interactive influence of time gradient and distance gradient in open-pit coal mining， soil microorganisms and soil enzyme activities all have a certain response， and as the interference time gradient decreases， the response degree of soil biological activity decreases， and the response of soil factors changes.Only individual factors are related to soil biological activity.