Nano-SiO2 microspheres were prepared by sol-gel method and grafted with silane coupling agent KH550, then composited with chitosan/starch solution and applied in fresh- keeping packaging of cherry tomatoes. Scanning electron microscopy, infrared spectroscopy, particle size analysis were used to characterize the optimum technological paramentres and grafting effect of nano-silica microspheres. The preservation effect of chitosan/starch solution with the different mass fraction of nano-silica microspheres was analyzed. The results showed that: the uniform and monodisperse microspheres were prepared by adding 5 mL ammonia，2.8 mL tetraethyl orthosilicate，40mL ethanol and slow droipping method；the nano-SiO2 microspheres modified by silane coupling agent KH550 could improve the performance of composite membrane; when the content of modified nano-SiO2 microspheres in chitosan/starch composite film was 3%, the fresh-keeping effect was better.