Abstract: This patent design is involved in leakage-proof sealing design for a plastic bottle cap, which works with water dispenser. Technique issue: It focuses on designs of an interior water outlet lid at leakage-proof and on design of a pliably wedged sealing ring in the cap. The patent design aims at eradicating phenomena that an interior water outlet lid drops in water to create secondary pollution and rescinding use of a leakage-proof foaming gasket in the cap. Embodiment: 1. Employ a kind of non-toxic, odorless, and food grade aluminum foil lid to seal the interior water outlet in a cap. 2. Add a fixed pliably wedged ring onto interior sidewall of a cap to replace a mobile polyethylene foaming gasket. Effects: The patent cap design possesses simple structure, hygiene, and strong sealability. It can eradicate leak from plastic interior lid, rescind foaming gasket use, reduce cost and avoid secondary pollution to bottled water.