To solve the problem of flux depression,membrane fouling and separation efficiency decline of nanofiltration mem-brane after long term operation in the separation of Mg ²⁺/Li ⁺ from salt lake brine,the pilot-scale study using ceramic ultrafil-tration membrane as a nanofiltration pretreatment measure for qualified lithium extraction solution from salt lake brine was conducted.The pilot facility was set in the lithium extraction workshop and the qualified solution from lithium extraction pro-cess was used as influent.The results showed that,the ceramic ultrafiltration membrane continuously and stably ran under the flux of 300 L/（m ²·h） both under the normal water quality conditions of influent turbidity below 50 NTU at low temperature in winter and under the condition of extreme influent turbidity of qualified liquid rising to 50~170 NTU,the filtration time was in the range of 30~50 min/cycle.The permeate turbidity was stably below 0.1 NTU,which was better than the influent quality re-quirement of subsequent nanofiltration.