The invention discloses a sealing element for a bottle mouth and relates to a sealing element used for sealing a bottle mouth. The sealing element includes a supporting plate. The supporting plate is covered with an elastic device. The elastic device is covered with a waterproof film. The side face of the supporting plate is provided with a plurality of elastic cords. One elastic cord is provided with a buckle device, and other elastic cords are provided with plugs matched with the buckle device. Compared with the prior art, the sealing element has a sealing effect for bottles of different shapes and calibers, and therefore the problem that in the past, bottles of different calibers need bottle caps of different specifications for sealing is solved.