The invention discloses an active air cooling and phase change cooling composite battery thermal management system and a working method thereof. The system is composed of a thermal management system box body, a battery pack, phase change cooling devices, a supporting column, a supporting plate, cooling air inlets, cooling air outlets and an electric push rod, wherein two groups of cooling phase change devices which are stacked up and down are arranged, the phase change devices are matched with the battery pack, two groups of air inlets and air outlets are formed, when one group of phase changecooling devices works, the other group of phase change cooling devices and the corresponding air inlets and air outlets form a cooling system of the phase change devices, a phase change material is cooled and solidified through forced air cooling; when the working phase change devices fail in heat, the phase change devices in the cooling system are transmitted to form a new working system together with the battery through the electric push rod, at the moment, the phase change cooling devices failing in heat, the other air inlet and the other air outlet form a new cooling system. The system isadvantaged in that the temperature control effect of the phase change temperature control device in the system is remarkably improved, and the defect that the phase change device cannot continue to work after heat charging fails is effectively overcome.