Abstract: Abstract: Fresh fruits and vegetables with a high content of water are easily lost to spoilage by a variety of microorganisms, resulting in short shelf life. Specifically, penicillium (P. steckii) has been the most harmful and frequent disease in postharvest storage of fruits, such as mango and citrus, which are easily infected by moldy pathogens. Fortunately, the nano-TiO2 particle has widely been used to preserve fruits and vegetables, due mainly to the high chemical stability and antibacterial properties. Two reasons can be attributed to the preservation mechanism. 1) Ethylene (C2H4) under ultraviolet (UV) irradiation has normally been decomposed into carbon dioxide (CO2) and water (H2O) in the fruits and vegetables packaging, where the concentration of CO2 increases, while that of C2H4 decreases. As such, the respiration and ripening rate of fruits and vegetables can be effectively delayed by the gas change, thereby controlling the water loss. 2) Microorganisms are composed of organic compounds, such as bacteria and fungi. Strong oxidation can denature the protein, thus inhibiting the growth of microorganisms or even killing, where Reactive Oxygen Species (ROS) has been produced by nano-TiO2 under light conditions. Nevertheless, the biosynthesis of nanomaterials has attracted much more attention, with the highly demand for renewable and non-toxic chemicals in recent years. Correspondingly, the nano- TiO2 biosynthesis can be assumed as a bottom-up approach, including the main reaction of reduction/oxidation without toxic chemicals involved in the synthesis process, particularly suitable for pharmacy, biomedicine, and food. In this study, nano-sized TiO2 particles were prepared by biosynthesis, where the mango leaf extract was taken as the reducing agent, while metatitanic acid (TiO(OH)2) as titanium source. An investigation was also made to explore the effects of extraction times on the reduction ability of mango leaf extracts. Moreover, the Response Surface Method (RSM) in a single factor experiment was selected to optimize the biosynthesis process of nano-TiO2. The nano-TiO2 particles were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), together with antimicrobial properties against P. steckii. The results showed as follows. The yield of nano-TiO2 increased with the extension of extraction time when extracting mango leaves. Specifically, the yield of nano-TiO2 was 86.74%, when the extraction time was 30 min, which was not significantly different from 87.62% and 87.93% when the extraction time was 40 and 50 min. An optimal combination of synthesis process was achieved, where TiO(OH)2 addition 0.65 g, reaction time 10.2 h, calcination time 2 h, and calcination temperature 786 °C. In this case, the photoinduced degradation rate of nano-TiO2 was 96.24%, and the standard deviation from the theoretical value was 0.6%. In addition, the XRD pattern demonstrated that the biosynthetic nano-TiO2 was anatase type. SEM images showed that the TiO2 nanoparticles obtained by biosynthesis were quasi-spherical, with the distribution of particle size in the range of 20-40 nm and fewer aggregates, but the modified nano-TiO2 presented a smaller particle size and fewer aggregates, indicating the better dispersion. Furthermore, the biosynthesized TiO2 nanoparticles exhibited a certain inhibitory effect on P. steckii, whereas, the modified nano-TiO2 performed a better antimicrobial effect under the induction of ultraviolet (UV) light. More importantly, the modified nano-TiO2 in composite coating behaved an obvious inhibitory effect on P. steckii. Consequently, the biosynthesized nano-TiO2 can widely be expected to serve as the preservation of fruits and vegetables to maintain the quality and prolong the storage life. This preparation process can provide a strong theoretical reference for the synthesis of nano-TiO2 with better photoinduced antibacterial properties.