Abstract: In this paper, four factors including nano-TiO₂ particle size, ultrasonic power and time, the amounts of Tween 80 on the antibacterial property of chitosan/nano-TiO₂ composite coating film were investigated. The mechanical properties of the composite films with different adding amounts of nano-TiO₂ particles were characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TG). The antibacterial test results in the single factor test showed that the antibacterial effect of the composite coating film on Staphylococcus aureus was the best under the conditions of the diameter of nano-TiO₂ 30 nm, the ultrasonic power 80 W and the ultrasonic time 50 min, the amount of Tween 80 0.5%, respectively. SEM analysis showed that the particles of nano-TiO₂ could be well encapsulated in chitosan but with some agglomeration. TG results also indicated that the chitosan-TiO₂ composite coating films exhibited the better thermal stability.