The invention discloses a vehicle-mounted distributed energy supply system and belongs to the technical field of new energy vehicle power. The vehicle-mounted distributed energy supply system comprises an electric energy supply system, a mechanical energy supply system, an electric energy management controller and a vehicle control unit. The electric energy supply system is used for generating electricity and supplying electric energy to a vehicle. The mechanical energy supply system supplies power to the vehicle and supplies reactive materials required for electricity generation to the electric energy supply system. The electric energy management controller monitors the energy state of the electric energy supply system, and first preset threshold value electric quantity and second preset threshold value electric quantity are set in the electric energy management controller. The vehicle control unit is used for monitoring energy state information of the electric energy supply system and the mechanical energy supply system and controlling the work mode of the distributed energy supply system according to the detected energy state information and the vehicle traveling working condition. The vehicle-mounted distributed energy supply system is provided with the two independent energy supply systems and can work in the optimal work mode, the electric energy supply system generates electricity through a chemical method, the pollutant emission is low, and the energy use efficiency is high.