A pull-rotary filter switch with a fool-proof effect to avoid accidentally cut off power supply includes a rotary switch device, a transmission line and a filter. The rotary switch device has a casing, a fixing seat, a substrate, a pull-rotary button and a contact terminal. The casing has an opening and a through hole. The fixing seat has a penetrating hole, a first eccentric hole and a second eccentric hole. The substrate has a conductive point and a board hole. The contact terminal is disposed on one end of the eccentric rod and contacted to the conductive point. The transmission line is electrically connected to the transmission line, which passes through the shaft hole, the penetrating hole, the board hole, and the through hole to electrically connect to the conductive point.