The separator is an important part of lithium-ion batteries, and obtaining high-performance separators is a significant way to improve the battery performance. In this paper, the cellulose separator which can be used in lithium-ion batteries was prepared by chemical cross-linking. That is, a cellulose-based cross-linked structure membrane was synthesized withcellulose acetate (CA) and cross-linking agent hexamethylene diisocyanate (HDI) by a condensation reaction. The experimental results showed that: compared with the commercial polyethylene separator, this membrane had excellent thermal stability, mechanical strength and electrochemical performance, which hardly shrinked at 200 ?C for 30 minutes. The tensile strength could reach 30.70 MPa , The assembled lithium-ion battery also had good cycle charge and discharge performance, and the specific discharge capacity of the battery maintained at 95% after 100 cycles under the charge and discharge conditions of 0.5 C/0.5 C.