The present disclosure relates to the technical field of heat pumps, in particular to an air source CO2 heat pump system for preventing an evaporator from frosting by using heat of a heat regenerator. The air source CO2 heat pump system mainly includes an air source heat pump system, a regenerative heat exchange tank and a cooling pump. Through the regenerative heat exchange tank, on the one hand, the temperature drop of regenerative heat of the system is further increased and throttling loss is reduced; on the other hand, the heat generated by the regenerative temperature drop is configured for heat storage used for defrosting, and configured for overheating temperature rise.