Abstract: [Objective] In China, there are many iron tailings abandoned nowadays, their ecological restoration has always been the focus of attention. It is well known that the number of soil microbe and the soil enzymes activities are the important indicators of soil biological properties, and also to a certain extent affect the soil fertility. Study on the soil microbial number and soil enzyme activities in iron tailings under different vegetation restoration models can provide scientific basis for the ecological restoration of iron tailings wastelands. [Method] In this study, the soil biological properties of iron tailings under natural restoration and plantation in Qian'an city were targeted, and based on random samples and tracking observations, the soil microbial quantity and soil enzyme activities of different restoration chronosequences in iron tailings were detected and analyzed.[Result] The quantity of soil microbe was increased with the vegetation restoration years, and for the spatial distribution the quantity was decreased with the depth of soil. Of their total quantity, the number of bacteria was the most, followed by actinomyces, and the number of fungi was the least. Plantation had more soil microbial quantity and a higher growth rate than the naturally restored vegetation. After 11 years of restoration, compared with natural restoration, the quantity of bacteria, fungi and actinomyces in 0-20 cm layer of the plantation increased by 14.25%, 80.56% and 75.19%; the quantity of bacteria, fungi and actinomyces in 20-40 cm layer of the plantation increased by 22.78%, 125.80% and 0.51%; and the quantity of bacteria, fungi and actinomyces in 40-60 cm layer of the plantation increased by 8.41%, 145.45% and 55.70%. The soil enzyme activities also increased with the increase of the restoration year, and decreased with increasing soil depth. The soil enzyme activities in plantation were higher than that in natural restoration. After 11 years, compared with natural restoration, the activities of soil catalase, soil invertase, soil urease and soil phosphatase in 0-20 cm layer of the plantation increased by 26.39%, 51.11%, 51.68% and 49.60%; the activities of soil catalase, soil invertase, soil urease and soil phosphatase in 20-40 cm layer of the plantation increased by 23.69%, 5.13%, 19.83% and 46.20%; and the activities of soil catalase, soil invertase, soil urease and soil phosphatase in 40-60 cm layer of the plantation increased by 4.26%, 3.45%, 1.38% and 134.60%.[Conclusion] Vegetation recovery in iron tailings wastelands could improve soil biological properties. Both the natural restoration and plantation could improve the quantity of soil microbial and the activities of soil enzyme in iron tailings, and the improvement effect of plantation was better than the natural restoration.

Key words: soil biological properties, soil microbe, enzyme activity, iron tailings, restoration pattern