Abstract: The membrane separation is a kind of emerging separation technology.In order to extract lithium from salt like brine，the diluted salt lake brine being as feed water were filtrated with a commercially available DK nanofiltration membrane so as to investigate the possibility of separation of Mg2+/Li+ by nanofiltration method.Under the experimental operating conditions，the results showed the membrane separation permeate factors（SF） of Mg2+/Li+ with three feed waters owning differ?鄄 ent compositions were all less than 0.1 and the Mg2+/Li+ mass ratios were reduced from 48.50，42.31，and 28.30 in the feed warters to 4.04，3.21，and 1.86 in the permeates.It proved the feasibility of extracting lithium from salt lake brine by nanofiltration.Meanwhile almost all Ca2+，SO42- and at least 73.81% B ware rejected efficiently in the retentates.The permeates and the retentates can be used to extract relevant inorganic salts.So nanofiltration will give the possibility to support comprehensive utilization of salt lake brine.

Key words: salt lake brine, lithium, nanofiltration