In order to solve too long maintenance power line and time-consuming in outdoor of substation, and when many maintenance team are working, wiring is confusion, which is easy to create security risks and other problem, a solar portable maintenance power box which using electric/photoelectric complementary technology, is designed from appearance structure, the grid/solar input module, control circuit of battery and inverter. It is tested by using simulation of Matlab/Simulink. Finally, the contrast test is proved to improve efficiency and reliability of maintenance in the substation.