The invention provides a forming water tank. The forming water tank comprises a tank body and a release film sheet, wherein the tank body comprises a bottom plate and a groove wall, one surface of thebottom plate is an inner bottom surface, at least one bite structure is formed on the inner bottom surface, the groove wall protrudes into the inner bottom surface and surrounds the edge of the bottom plate, and the release film sheet is attached to the inner bottom surface and the release film is embedded into the bite structures. By arranging the bite structures on the bottom plate, the bitingforce between the bottom plate and the release film is enhanced, peeling of the release film is avoided, and the durability of the release film is increased.