Soil nutrients, enzyme activities, and t heir correlations during land use change in the semiarid area of the Loess Plateau are studied.Results show that catalase activit y may indicate the right transformation condition of available P and available K in alfalfa land and organic matter, total N, and alkaline N in waste- land, as well as the negative transformation condition of available P in Sea-buckthorn land, but it may not indicate the fertilizer condition in field soil.Polyphenol oxidase activity may indicate the right transformation degree of organic mat ter and total N in field soil and the negative transformation degree of organic matter and total N in vegetable garden and orchard, but it may not indicate the hum us transformation degree in soil.Invertase activity may indicate the right transformation degree of alkaline N in field soil, vegetable garden and orcha rd, alfalfaland, and wasteland and the negative transformation degree of alkaline N in sea-buckthorn land.At the same time, it may fully indicate the negative transformation degree of available P in wasteland and the right transformation degree of other nut rients.Urease activit y may indicate the fertilizer level of total N, alkaline N, and organic matter in vegetable garden and orchard.Phosphatase activity may indicate the right t ransformation condition of available P in vegetable garden and orchard, field soil, and wasteland, but it may not indicate the phosphorus transformation condition of other land uses.