A charging power system with low standby power consumption includes a system control unit and a plurality of charging modules. The charging modules are electrically connected in parallel and receive an input power source. Each charging module includes an auxiliary power supply unit, a power conversion unit, and a charging module control unit. When the charging modules enter standby conditions, the system control unit produces auxiliary control signals and the charging module control units produce main control signals to correspondingly control the auxiliary power supply units to stop outputting auxiliary power. Accordingly, it is to reduce standby power consumption and increase overall efficiency of the charging power system.