The responses of soil trace elements to green manure fallow were investigated to provide reference for soil nutrient management and agricultural production in the large region of farmland. Based on the three-year multi-point monitoring data in the dryland farming area of central Gansu, six indexes of soil trace elements, including available Fe, available Mn, available Cu, available Zn, available Mo, and available B, were selected to compare and analyze the differences of soil trace elements before and after fallow planting of green manure. The results showed that: (1) Compared with the basic soil, after three years of fallow, the contents of available Mn, available Cu, and available Zn in soil were significantly increased by 18.8%, 22.5%, 14.3%, respectively (p＜0.05). The contents of available Fe and available B showed significant decreasing trends (p＜0.05), while available Mo did not change significantly. (2) Regression analysis showed that the magnitude of variation of available Fe, available Mn and available Cu were all negatively linearly related to the basal content of trace elements before fallow, while effective Zn and effective Mo were all negatively logarithmic (p＜0.05), and had a significant enhancement effect on agricultural soils with basal content of available Mn, available Cu, available Zn, and available Mo of less than 8.0, 0.9, 0.3, 0.06 mg/kg, respectively. There were significant negative linear correlations (p＜0.05) between the magnitude of changes in available Fe, Mn, Cu and the pre-fallow basic nutrient contents of soil organic matter and total nitrogen. (3) Further correlation analysis of trace elements and macronutrients in the soil after fallowing showed that available Fe, Mn, and Zn were significantly positively correlated with soil organic matter, total nitrogen, available phosphorus and available potassium. Except for available Mo, the other five trace elements were significantly negatively correlated with soil pH. In conclusion, the implementation of fallow mode of green manure planting can improve the contents of available Mn, Cu, and Zn in the dryland farming area of central Gansu to some extent, particularly good for soils of Mn-deficient, and it is more effective for soils with low basic soil nutrient content and alkaline soils.