A current compensation module for a charging apparatus, so as to output a control signal to a driving circuit to adjust and control a charging current, which is outputted from a power conversion module to a battery module, wherein when the charging apparatus outputs the charging current, there can be operated in a first start-up phase, a second start-up phase, and a third start-up phase, the current compensation module comprising: a transition unit, for executing a clamping control for clamping an internal-signal voltage in the current compensation module at a first voltage for implementing of the current compensation module and the charging apparatus, wherein when the charging apparatus is operated in the first start-up phase to output the charging current is outputted, the transition unit executes the clamping control to make the internal-signal voltage increasing from the first voltage with the gradually increased charging current; a proportional controlling unit, electrically connected to the transition unit, wherein when the internal-signal voltage attains to a second voltage, and the charging current is lower than a rated output current, the charging apparatus is operated in the second start-up phase, thus the proportional controlling unit is arranged to output a proportional controlling signal to control and adjust the charging current by the power conversion module through the driving circuit so as to increase the charging current; and an integral controlling unit, electrically connected to the proportional controlling unit via a conjunctional point and electrically connected to the transition unit, wherein when the charging current attains to the rated output current, the charging apparatus is operated in the third start-up phase, thus the integral controlling unit generates a proportional-integral controlling signal with the proportional controlling unit through the transition unit for maintaining the charging current with the rated output current so as to charge the battery module with a constant current. a transition unit, for executing a clamping control for clamping an internal-signal voltage in the current compensation module at a first voltage for implementing of the current compensation module and the charging apparatus, wherein when the charging apparatus is operated in the first start-up phase to output the charging current is outputted, the transition unit executes the clamping control to make the internal-signal voltage increasing from the first voltage with the gradually increased charging current; a proportional controlling unit, electrically connected to the transition unit, wherein when the internal-signal voltage attains to a second voltage, and the charging current is lower than a rated output current, the charging apparatus is operated in the second start-up phase, thus the proportional controlling unit is arranged to output a proportional controlling signal to control and adjust the charging current by the power conversion module through the driving circuit so as to increase the charging current; and an integral controlling unit, electrically connected to the proportional controlling unit via a conjunctional point and electrically connected to the transition unit, wherein when the charging current attains to the rated output current, the charging apparatus is operated in the third start-up phase, thus the integral controlling unit generates a proportional-integral controlling signal with the proportional controlling unit through the transition unit for maintaining the charging current with the rated output current so as to charge the battery module with a constant current.