Erosion directly affects soil characteristics and has a significant effect on the formation and stability of the soil microbial community. Soil microbial biomass not only plays a significant role in energy flow and nutrient cycling, but it also shows great sensitivity to changes in soil environment. Soil enzyme activities are indicative of the functional diversity of the soil microbial community, as they are closely associated with soil microbial biomass. To reveal the effect of different erosion environments on soil microbial biomass and soil enzyme activities, soil samples were collected from the Chengjiawa watershed, located in the Yanhe watershed of the hill and gully region of Ansai County, Yan'an, Shaanxi Province, China. Soil samples were collected from five erosion environments in the valley, at depths of 0-10 cm and 10-20 cm. We studied the characteristics of soil microbial biomass including carbon, nitrogen, and phosphorus, soil enzyme activities including soil urease, invertase, and alkaline phosphatase, and correlations between soil microbial biomass and enzyme activities. The results showed that: (1) Soil microbial biomass carbon, nitrogen, and phosphorus were significantly different between the 0-10 cm and 10-20 cm soil layers; soil microbial biomass carbon and phosphorus in the shaded lower slopes were higher than in the other tested environments, whereas in the sunny middle slope and the hill top they were lower than in the other tested soil environments. The difference between the shaded lower slopes and sunny hill top were significant. Soil microbial biomass nitrogen in the sunny lower slope was significantly higher than in the other tested soil environments. Overall, soil microbial biomass of the ditch slope was higher than in the other tested environments. This suggested that the erosion affects the soil microbial properties, and that soil nutrient accumulation and mineralization ability of soils on the downhill slope were higher than in other tested locations. (2) Soil urease, sucrase, and alkaline phosphatase activities were higher in the 0-10 cm layer than in the 10-20 cm layer. In different erosion environments, soil enzyme activities were higher in the shaded middle slope than in any other tested environments, while they were the lowest in the sunny middle slopes. Soil alkaline phosphatase activity did not significantly differ between different soil environments. Soil invertase activity in the shaded middle slopes was significantly different from the other four types of erosion environments. The difference in soil urease activity between the shaded lower slope and other tested environments was significant. Comparisons showed that the environment exposed to erosion affected the properties of soil enzyme activities; the responses of soil invertase and urease were more sensitive to changes in the soil environment. (3) Pearson correlation analysis showed that soil microbial biomass carbon, nitrogen, and phosphorus were significantly positively correlated with each other, as were the soil urease, sucrase, and alkaline phosphatase activities. There was a significant positive correlation between soil microbial biomass and soil enzyme activities, which suggested that these two properties were closely linked and inseparable components of the soil microbial community. Different environments exposed to erosion have diverse levels of soil organic matter content, different physicochemical properties of the soil, diverse forms of soil microbes, and differ in the amount of soil microbial biomass and soil enzyme activities. These differences were reflected in the soil quality, vegetation types, and resistance to soil erosion.