A charging base has a bottom case, a printed circuit board (PCB) and a top case. The bottom case includes at least one drainage hole. The PCB is mounted in the bottom case and includes a mounting hole, a positioning block and charging terminals. The positioning block is attached to the PCB and has through holes. The charging terminals are secured to the positioning block and have apertures. The top case covers the bottom case and includes terminal holes and a top enclosed wall. The top enclosed wall is secured around the positioning block. Therefore, when water accidentally enters the charging base via the terminal holes, the water will sequentially flow through the apertures of the charging terminals, the through holes of the positioning block and the mounting hole of the PCB and subsequently drain out of the drainage hole of the bottom case.