There is a number of conditions for the main generator of more electric aircraft to supply to the power grid. Firstly the generator has to be excited. When the speed of the generator is normal, the generator voltage meets the requirements, and the external power supply is broken off, then the generator contactor should be turned on to supply to the power grid. This design is based on C8051 microcontroller and it’s peripheral circuit, in order to simulate the conditions of the main generator of more electric aircraft supplying to the power grid. And the result is displayed on the LCD(Liquid Crystal Display). The design includes hardware circuit design and software programming. Final work is debugging and verification of the device, and the experimental results can meet the original intention.