The dynamics of nutrient release and organic matter decomposition of Chinese milk vetch as green manure were studied in paddy fields,which the green manure were wrapped in net nylon bags and embedded in plow layer in tobacco fields.The results showed that there was no significant influence on the organic matter decomposition rates and the nutrient release dynamics of Chinese milk vetch under different fertilization.The relationship between the release of dry matter,N,P and K in Chinese milk vetch and decomposing time was fitted by a firstorder kinetic equation.The maximum decomposition rate of Chinese milk vetch under different fertilization was 64.8%～68.3%,and the maximum accumulative release rate of nitrogen,phosphorus and potassium was 84.2%～86.7%,85.3%～89.3% and 89.9%～98.0% respectively.The nutrient release rate was in the order with potassium > phosphorus > nitrogen.The nutrient release of Chinese milk vetch was concentrated in the first 15 days after the Chinese milk vetch was embedded in the fields,so the management of nutrient during the late growth period of rice was very important.Chinese milk vetch could activate potassium in soil in a short time,that about a growth period of rice. But the soil available potassium content was lower than those treatments with chemical potassium fertilizer application.So that,planting Chinese milk vetch and returning to field cannot entirely replace chemical fertilizer effect.