Diseases and insect pests can seriously affect the yield and quality of greenhouse vegetables. Spraying chemical pesticides is currently the most effective method to control diseases and insect pests. However, the extensive use of chemical pesticides, on the one hand, leads to pathogenic bacteria and pests becoming resistant to chemical pesticides, which eventually makes prevention and control more difficult and, on the other hand, causes serious environmental pollution and leaves pesticide residues that are a threat to people’s health. Developing green control technology for diseases and insect pests is an important way to reduce the amounts of chemical pesticides used. A new type of ozone sterilizer device, named multi-functional plant protection machine, and an information management system was designed. The device included mainly ozone generation, circuit control, high-speed fan, trap lamp, environmental data acquisition, and other modules. All the modules were controlled by a STM32F103 microprocessor. The machine used a high-voltage discharge method to produce ozone that could be rapidly and evenly diffused into the whole facility space through the high-speed and large-volume fan and special air duct. At the required concentration, the ozone could oxidize and decompose eggs and larvae of insects, bacteria, and fungi, and inhibit virus reproduction. The device had yellow and blue lights to attract adult insects, which were then sucked into the machine by the fan and killed. The information management system had IoT-based architecture and included a mobile app. This web-based information management system interacted mainly with the data center to realize intelligent management of plant protection data. The device could be controlled remotely using the mobile APP for real-time adjustment of the fan’s wind speed, adjustment of ozone release, collection of environmental data, and opening of the trap lamp and other functions. The multi-functional plant protection machine was tested for its ability to control cucumber powdery mildew and Bemisia tabaci in several greenhouse facilities. The test results showed that after using the equipment during the whole growth period of the cucumber, the disease index of cucumber powdery mildew was controlled at 5.9, and the control effect on Bemisia tabaci reached 89.5%. The multifunctional plant protection machine effectively controlled cucumber powdery mildew and Bemisia tabaci in the greenhouses. The research result provided a reference for green control of diseases and insect pests in facilities that grow vegetables.