The practical application of zinc ion batteries (ZIBs), a promising large-scale energy storage system, is limited by the lack of mechanical strength, large thickness and high interfacial impedance of traditional glass fiber separators, which seriously restrict the cycling stability of zinc anodes. Therefore, the development of new separators that can effectively inhibit the growth of dendrites and thus enhance the stability of zinc anodes remains a key challenge to be tackled. For this purpose, a TiO2-modified composite separator based on cellulose nano fibre (CNF) was designed, aiming to enhance the cycle life of the battery by modulating the zinc ion transport process. By exploring the effects of TiO2 loading on the performance of the separator, it was found that the 15%TiO2/CNF separator exhibited excellent mechanical properties, which ensured adequate safety of the assembled battery. Its assembled Zn||Zn symmetric batteries can also operate stably at high current densities, ensuring the stability of the batteries. The assembled Zn||MnO2 full cell has excellent durability and superior capacity retention, with a capacity retention up to 71% after 1000 cycles. The prepared TiO2/CNF separator based on the direct interface engineering strategy provides a new idea for the preparation of high-performance zinc ion battery separators.