The invention discloses a liquid supply device and a liquid supply method for a sanitary foam applicator of a closestool. The sanitary foam applicator is composed of a power supply, an
air pump, a water pump, a foam generating device, the liquid supply device, a
silica gel tube, a housing and the like. According to the liquid supply device provided by the invention, the liquid supply device is composed of a container, the water pump, a pipeline and a closestool water tank, wherein the container is sealed; and a water inlet hole, a liquid outlet hole, a
liquid injection hole and a
liquid injection hole plug are reserved in the wall of the container; the water inlet hole communicates with water of the closestool water tank; by virtue of the
liquid injection hole, a
foaming agent is added and
injector, and the liquid injection hole is sealed by virtue of the hole plug; and the liquid outlet hole of the container is formed in the upper side of the container and is connected to the water pump. According to the liquid supply method provided by the invention, most part of the container is used for accommodating the
foaming agent and the other part is used for keeping water; the
foaming agent, which is higher in
specific gravity, is kept in the lower side of the container while the water, which is lower in
specific gravity, is kept in the upper side of the container, and some of the foaming agent can be dissolved in the water, so that foaming liquid is formed; and the foaming liquid in the container is pumped into the foaming device by virtue of the water pump. The water, at an equal amount, rushes into the foaming agent as the foaming liquid is pumped away, so that the foaming agent continues to be dissolved and foaming liquid is rapidly formed, repeating in such way.