A bottle cap capable of being opened by one press, comprising a bottle mouth (11) and a bottle cap (1), and further comprising a positioning ring (3), a fixing ring (10), and an oval elastic snap ring (8). A slot (13) is provided between the positioning ring (3) and the fixing ring (10); the two major axis ends of the elastic snap ring (8) are located in the slot (13); either of the two major axis ends of the elastic snap ring (8) is provided with a press piece (7); a groove (12) is circumferentially formed on the side wall of the bottle mouth (11) at a position corresponding to the elastic snap ring (8); the two minor axis ends of the elastic snap ring (8) are located in the groove (12) to lock the connection of the bottle cap (1) to the bottle mouth (11), and are configured to stretch as the press piece (7) is pressed, so as to disengage from the groove (12) and enter the slot (13), thereby unlocking the connection of the bottle cap (1) to the bottle mouth (11).