The decomposition dynamics of the returned straw of rape,Chinese milk vetch and their mixtures with different proportions in submerged paddy soil were studied under pot experiment.The result showed that the decomposition rate of rape straw,Chinese milk vetch and their mixtures in soil was fast in the first 10～20 days,slowed down after that,and then kept stable.The nutrient release rate was K>P>N>C.At 90 days after incubation,the K release rate was 95.09%~97.17%,P release rate was 62.65%~87.14%,N release rate was 70%~76.48%,and C release rate was 39.53%~64.69%.At the end of the experiment,the decomposition rate of the Chinese milk vetch and rap straw were 60.07%,40.8%,respectively.The decomposition rate of mixtures was improved when Chinese milk vetch was mixed in,and the rape straw decomposition rate was boosted with the increasing amount of Chinese milk vetch.