The invention belongs to a mobile substation technology, and in particular relates to a substation replacement power supply method using 10kV mobile medium voltage and a protection vehicle. The methodcomprises the following steps: transporting the mobile medium voltage and the protection vehicle in place, carrying out partial replacement on wiring of a power distribution device, carrying out a joint debugging test on a substation field, and carrying out commissioning of a substation. The power supply method is mainly used for transporting the mobile medium voltage and the protection vehicle to the substation for performing on-site alternative power supply as well as rescue and disaster relief when the power distribution device in the substation is partially overhauled or failures suddenlyoccur. Furthermore, the invention provides an ideal of replacement power supply of the 10kV mobile medium voltage and the protection vehicle in the substation, thus having better practicality and reliability.