The invention relates to a waterproof socket equipped with a draining tank and a secondary lock. The waterproof socket comprises a socket housing, a socket sheath, binding posts, and the secondary lock. An annular gap is formed between the top of the socket sheath and the socket housing. The top surface of the socket housing is equipped with multiple binding post holes. Each binding post is arranged corresponding to a binding post hole. The secondary lock is inserted into the socket housing. The socket sheath is provided with a secondary lock opening. The draining tank is disposed on the socket sheath. By means of the secondary lock, a plug is prevented from shaking after being plugged into the socket. The draining tank is disposed on the socket sheath so as to be capable of directly draining water entering a connector, thereby improving waterproof performance. A sealing ring is provided in order to improve the waterproof performance of the socket.