Automatic water supply device of water closet

The utility model discloses an automatic water supplying device of a water closet, which comprises a water supplying passage, a water outlet passage and a control valve, wherein a valve body and a valve cap are installed in a valve seat of the control valve, the valve body is provided with a connecting passage for communicating the water supplying passage and the water outlet passage, a water-stopping rubber pad controlling the on-off of the connecting passage is arranged between the valve body and the valve cap, a closed control water cavity is formed between the valve cap and the water-stopping rubber pad, the valve cap is provided with a water outlet of the control water cavity, and t he water-stopping rubber pad is provided with a water inlet of the control water cavity; a lever is hinged with the valve seat, one end of the lever is connected with the float barrel, and the other end of the lever is provided with a convex block capable of sealing the water outlet of the control water cavity; the outer wall of the water outlet passage is provided with a ventilating hole which is positioned above the prescribed water storing level. The utility model has the advantages of simple structure, high water supplying speed, quiet water supply, not only can prevent siphon and avoid result in the pollution of a water resource, but also can also automatically replenish water to a water closet.