A rotating tray microwave vacuum (RTMV) dryer was designed to solve the problems of uneven heating of materials, difficult control of hot spots and poor dried quality. The machine was composed of drying box, control system, vacuum system, transmission system, water circulation system and heating system. In order to make the material heating uniformly, the main axis with five evenly distributed rotating bracket was placed into the microwave vacuum drying chamber and driven by a stepper motor. During the drying process, the material was rotated constantly around the main axis with a horizontal level. The vacuum system can remove the moisture evaporated from the material in time during the vacuuming process. The combination of dryer and water circulation system ensured the normal operation of vacuum pump, so as to maintain the vacuum pressure of drying chamber consistently. The control system can be divided into five modules: the main control, A/D conversion, expansion, output control and display screen. The system took the P89V51RD2FN chip as the core to control the coordination of each module, which can adjust the drying pressure in the drying room between vacuum and normal pressure precisely. The papaya was used as the material for the performance test and compared with the traditional microwave drying method. The results showed that the carrying capacity of the dryer was increased by 80% compared with the latter. And the drying time was shortened by 43.8% at the same time. The unit energy consumption of papaya slices treated by RTMV dryer was about 29.8% lower than that by the conventional way. And the dehydration uniformity reached up to 97% with consistent color distribution between inner and outer of the dried sample, showing good drying uniformity of RTMV drying technology. The designed dryer ensured the uniform heating of materials, improved the drying efficiency and guaranteed the drying quality of materials, which provided a reference for the subsequent application.