The author, for the first time, made a study of ecological quantitative in group compose, number distribution, seasonal variation, vertical migrating etc. of the soil mesofauna in Heze Peony Garden. The result shows that Acari and Collembola are dominant groups of them. Seasonal fluctuation of the mesofauna density is positively related to soil temperature in a given range, so is the water content of soil to the number of soil mesofauna. The soil mesofauna tends to gather on soil surface, but the vertical migrating greatly varies in different seasons affected by climate condition, edatope, artificial factor and so on.