Abstract: Undisturbed soil cores were incubated in laboratory at different temperatures (-10, 5, 15, 25, 35 and 40 ℃) and moistures (29%, 58%, 85% and 170% of field water content, FWC) to analyze the effect of moss crusts, which were sampled from the natural vegetation area of Shapotou, on soil nitrogen transformation and their responses to hydrothermic factors. Results showed that immobilization was the dominant form of nitrogen transformation at the lower temperatures (<15 ℃), and when the temperature surpassed 25 ℃, the nitrogen transformation rate significantly increased. The nitrogen transformation rate in the moss-covered soil was more sensitive to temperature variation than in the bare soil, and the highest temperature sensitivity was at 85%FWC. It indicated that the existence and succession of moss crusts facilitated nitrogen transformation. In addition, the nitrogen transformation rates of two microhabitats increased initially and then declined with the increasing moisture, and the maximum nitrogen transformation rate was observed at 85% FWC. Significant interactive effects were found between temperature and moisture in the moss-covered soil. While, the greater enhancement in nitrogen transformation rate appeared at higher temperatures (25-40 ℃) and moderate moisture levels (58%FWC and 85%FWC). It was concluded that the existence and succession of moss crusts would increase the ability of soil nitrogen supply, promote nitrogen cycling and even contribute to the restoration of soil ecosystem.