Changes of soil physicochemical properties caused by land use conversion will significantly affect the content of nutrients (carbon, nitrogen and phosphorus) in soil and its stoichiometric characteristics. However, it is still unclear about the synergistic change between soil extracellular enzyme activity as well as its stoichiometric characteristics and soil factors due to the large environmental difference in different study areas. In this study, 7 kinds of typical land use types (Pinus massoniana land, Platycladus orientalis land, shrub land, terrace of vegetable field, terrace of abandoned land, sloped abandoned land, and sloped farmland) were selected as research objects in karst mountainous area. Taking the existing sloped farmland as the reference substance, the variation of 6 kinds of extracellular enzyme activity and its stoichiometric characteristics (β-1,4-glucosidase, cellobiohydrolase, β-1,4-xylosidase, β-1,4-N-acetylglucosaminidase, leucine aminopeptidase and acid phosphatase) were compared before and after the change of land use types using the spatio-temporal contrast method, and the relationship between them and soil physical and chemical factors were also analyzed. The results showed that soil nutrient status and enzyme activity were significantly improved after the conversion of land use type from sloped farmland to other, which not only significantly increased the nutrient content but also promoted the soil nutrient balance, because soil microorganism regulated the expression and activity of enzymes and the availability of phosphorus was greatly improved. In general, land use conversion from the sloped farmland to Pinus massoniana land and Platycladus orientalis land showed similar and best effect of soil quality improvement, whereas it also increased the restriction of soil phosphorus. In addition, soil total nitrogen content, C:N, N:P and pH value were the main factors driving the change of soil extracellular enzyme activity. The change of soil enzyme activity was consistent with that of nutrient content, and was regulated by the power of hydrogen. Therefore, the phosphorus input should be considered in the management of Pinus massoniana and Platycladus orientalis forest land in karst areas for alleviating the phosphorus restriction of artificial forest ecosystem.