Abstract: On the basis of the higher photocalysis characteristics of nanometer TiO₂, the technology of disinfecting and keeping fruit fresh by photocalysis using nanometer TiO₂ and flashlight was probed. The effect of the dosage of nanometer TiO₂, the times of flashlight, the distance between flashlight source and the target object and the original concentration of bacteria on disinfecting the bacteria(Bacillus Subtilis, Escherichiacoli) was studied by means of L₁₆(4⁵) orthogonal experiments. The experiment of keeping longan fresh by the photocalysis was also done. The results show that the photocalysis using nanometer TiO₂ and flashlight is effective for disinfecting the bacteria and extending longan shelf life. The optimal result was obtained: a)for disinfecting the bacteria, the dosage of TiO₂ is 4.0×10^-4 g/mL and the flashlight times is 30; b)for extending longan shelf life, the times of flashlight is 10，the distance between flashlight and the target object is 8 cm, the added amount of TiO₂ to plastic film is 1.3×10^-4～1.5×10^-4 g/cm².