The embodiment of the invention relates to the technical field of batteries, and discloses a pre-charging circuit and pre-charging method of a high-voltage battery pack. In part of embodiments of theinvention, in a charging process, after a control module determines that a voltage of the first end of a charging switch module and a voltage of a second end of the charging switch module accord witha first constraint relation, the charging switch module is closed, and a charging pre-charging module is disconnected; in a discharging process, after the control module determines that a voltage of afirst end of a main positive switch module and a voltage of a second end of the main positive switch module accord with a second constraint relation, the main positive switch module is closed, and amain positive pre-charging module is disconnected. The pre-charging circuit of the high-voltage battery pack can solve the problem that high current is generated at a closing moment due to the fact that the voltage difference between the two ends of the charging switch module and the voltage difference between the two ends of the main positive switch module are too large, and therefore influencesof the high current on the service life and controllability of the charging switch module and the main positive switch module are avoided.