Based on field sampling and laboratory experiments, distribution of microbial groups in two kinds of artificial forest ecosystems in the semi-arid region of the Loess Plateau was dynamically monitored. The results showed that there were significant differences in environmental factors between forest and wasteland in Beishan, Lanzhou. The soil water content, organic carbon and total nitrogen of forest land were higher than those of wasteland. Total phosphorus had no significant difference with vegetation type, but had significant difference with seasons. Soil temperature in summer > autumn > spring > winter, soil bulk density was negatively correlated with organic carbon and total nitrogen content. The distribution patterns of soil microbial groups in different vegetation types were as follows: bacteria > actinomycetes > fungi. The total abundance of microbial groups was higher in forest than those of barren land. Regression analysis showed that pH was positively correlated with the abundance of bacteria, actinomycetes and microorganisms (P < 0.05), which was negatively correlated with fungi (P < 0.05). There was a significant negative correlation between soil bulk density and the abundance of fungi (P < 0.05). Soil temperature was positively correlated with bacteria, fungi and total number of microorganisms (P < 0.05). Path analysis showed that pH had the largest direct path to bacteria, bulk density had the largest direct path to fungi, and soil water content had the largest direct path to actinomycetes. The results showed that the soil organic carbon, total nitrogen and total phosphorus in vegetation restoration area were higher than those in the wasteland, which indicated that the number and species of microorganisms were affected by the vegetation restoration, and the afforestation mode of mixed forest was suitable for the vegetation restoration in the north of Lanzhou.