N-methylmorpholine-N-oxide (NMMO) is considered as a green solvents of cellulose.Producing cellulose fibers and membranes by NMMO process is a more environmentally friendly technology.However, the production of NMMO is still costly, and most of the recovery is done through the conventional evaporation and precipitation processes, which are energy-intensive.In this article, a method of NMMO recovery by vacuum membrane distillation (VMD) using hydrophobic polypropylene (PP) hollow fiber membrane was proposed for the first time.Effects of feed-liquid's temperature,concentration as well as permeation-side vacuum pressure on the VMD flux and concentration efficiency were investigated,respectively.In this study, the optimal operating conditions were determined by orthogonal experiment.The orthogonal experiment results showed that the optimal operating conditions were that feed temperature at 80℃, feed concentration at 5wt% and permeation-side vacuum pressure at 0.09 MPa, while the maximum MD flux reached as high as 8.46 L/m2·h.