Abstract: This paper studied the process of decolorization,removing impurities and high efficient recycling NMMO in the coagulation bath of Lyocell.The results showed that after flocculation,ion exchanging and oxidation,the undissolved impurities and the soluble impurities harmful for redissolving and producing Lyocell fiber,especially the colored impurities and morpholine and metal ions like iron and copper in the coagulation bath could be removed effectively,and purified and recovered NMMO solution was colorless and transparent with no smell,very low electrical conductivity and oxidative recovery rate of NMM up to 96%.After vaporization and concentration,the recovered NMMO solution was redissolved,diluted,then used for washing the silk,and regenerated silk has good quality.