OBJECTIVE：To optim ize the ultrafiltration technology of enzymatic hydrolysate from Eucommia ulmoides peel. METHODS：The single factor test was adopted to investigate the effects of molecular weight of ultrafiltration membrane ，liquid temperature，operating pressure ，operating frequency ，membrane filtration time ，liquid concentration and pH on transfer rates of aucubin，geniposide and chlorogenic acid as well as solid removal rate in enzymatic hydrolysate from E. ulmoides peel. Setting the molecular cut off of fixed ultrafiltration membrane of 100 000，liquid concentration of 7 g/L，and pH value of 7，the ultrafiltration technology was optimized by Box-Behnken design response-surface methodology and validated with liquid temperature ，operating pressure，operating frequency and membrane passing time as factors ，using comprehensive scores calculated from transfer rates of aucubin，geniposide and chlorogenic acid as well as solid removal rate as indexes. RESULTS ：The optimal ultrafiltration technology of enzymatic hydrolysate from E. ulmoides peel was as follows as liquid temperature of 35 ℃，operating pressure of 0.5 MPa，operating frequency of 35 Hz and membrane passing time of 42 min. Results of validation tests showed that the comprehensive scores of the transfer rates of aucubin ，geniposide and chlorogenic acid as well as solid removal rate in enzymatic hydrolysate from E. ulmoides peel was 78.06％（RSD＝1.43％，n＝3），and its relative error with the predicted value （77.18％） was 1.14％. CONCLUSIONS ：The optimized ultrafiltration technology is stable and reliable ，and can be used for the ultrafiltration purification of enzymatic hydrolysate from E. ulmoides peel.