A portable computer and a charging method thereof are provided. The portable computer includes a charge integrated circuit (IC), a basic input/output system (BIOS) and embedded controller (EC), a south bridge chip, a north bridge chip and a central processing unit (CPU). After the portable computer is connected to a battery, the BIOS and EC controls the south bridge chip to read a sealed security bit of the battery and checks whether the sealed security bit equals a default value. The BIOS and EC controls the south bridge chip to read a battery data of the battery if the sealed security bit equals default value. The BIOS and EC controls the charge IC via the south bridge chip to charge the battery according to the battery data. The CPU controls the south bridge chip and the north bridge chip.