A bidirectional air pump assembly includes a pump mounting case, a valve and an air pump. The pump mounting case is mounted in an inflatable object and has a valve mounting hole. The valve is held in the valve mounting hole and includes an adapter with a valve port and a valve disk. The valve disk is attached to the adapter and has a disk body and at least one disk stop protruding from the disk body. The air pump is detachably mounted in the pump mounting case and connects to the valve port. Therefore, the air pump draws air out of the inflatable body through the valve port and a gap caused by the at least one disk stop abutting the air pump, which keeps the disk body from completely closing the valve port.