A micro grid frame structure design method and system are provided. The method includes the following steps: selecting the least number of AC/DC hybrid distribution devices based on power supply reliability indexes; when the number of the selected AC/DC hybrid distribution devices is a first set value, determining the frame structure of the micro grid by the connection mode of the selected AC/DC hybrid distribution devices; and when the number of the selected AC/DC hybrid distribution devices is larger than the first set value, determining the frame structure of the micro grid by the economicindex in the connection mode of the selected AC/DC hybrid distribution devices. According to the technical scheme of the invention, through the AC/DC hybrid distribution devices and the micro grid, the system runs stably, the cost of the power electronic converter is reduced, and flexible energy conversion is realized. The method and the system have great technical advantages.