Abstract: In this paper,urea and thiourea were used to modify the TiO₂ by N and S. The crystal structure and chemical composition of the modified composites were characterized by XRD and FTIR. The antibacterial and fresh-keeping effects of N and S modified TiO₂ and their starch composite films under visible light were studied. The preservation effect of composite starch membranes was evaluated by measuring the decay rate,weight loss rate and nutrient contents of the saint fruit during storage. The results indicated that the antibacterial rate of N,S modified TiO₂ composite film on E.coli reached 89% and 95%,respectively,which was 24% and 30% higher than that of pure TiO₂. The modified TiO₂ material could be uniformly dispersed in the corn starch composite film. The composite film was applied to the preservation of cherry tomato. Compared with uncoated group,the rot rate and weight loss rate decreased by 3.33% and 10.66% after storage for 8 days by the N-TiO₂ starch composite film. V_C contents,total acid contents and total sugar contents were 1.08,1.06,and 1.03 times of uncoated group,respectively. The rot rate and weight loss rate of S-TiO₂ starch composite film group decreased by 6.25% and 10.90%,respectively. V_C contents,total acid contents and total sugar contents were 1.11,1.12,and 1.08 times of uncoated group,respectively. N-TiO₂ and S-TiO₂ starch films could effectively inhibit the nutrient and water dispersion of cherry tomato,maintain its postharvest freshness and extend its storage life.