To provide the theoretical basis for reasonable determination of green manure turnover rate and chemical fertilizer application rate，a study was undertaken in uplands of northern Shaanxi. The decomposition and nutrient release characteristics of Vicia villosa were tested with different application amounts. Nylon net bags were used and three treatments were set up:low rate(30000 kg/hm²)，medium rate(45000 kg/hm²)and high rate(52500 kg/hm²). The results showed that in all three treatments，the V. villosa decomposed rapidly in the early stage and slowly in the late stage，and the final decomposition rate of dry matter reached 61.98% ～ 65.32% by the end of the experiment(75 d). Nitrogen，phosphorus and potassium released rapidly in the first 10 days，and nutrient release rates reached 69.10%～75.23%，72.25%～78.24% and 81.62%～90.02%，respectively，by the end of the experiment. The release rates and speeds of nitrogen，phosphorus and potassium in the different applications fitted well with the power function formula y=axb and the exponential decay model v=v0e-kx，respectively. Regression analysis showed that the release rates of the most readily available nutrients under different turnover rates decreased with the increase of turnover rate. With the increase of turnover rate，the maximum release rate of nitrogen nutrients increased first and then decreased，the maximum release rate of phosphorus gradually increased，and the maximum release rate of potassium gradually decreased. The delay effects of nutrient release caused by increasing application amounts were phosphorus>nitrogen>potassium，with 145～167，31～49 and 26～38 d for their full release，respectively. The general rules of decomposition and nutrient release did not change significantly with the increasing application amounts，but it affected the nutrient release rate and release speed. Therefore，the reasonable application amounts of Vicia villosa should be determined by nutrient requirements of crops.