The invention discloses a water level control device of a humidifier and the humidifier applying the same. The water level control device comprises a water tank and a base of the humidifier, wherein a steam generating chamber is arranged in the base; a drain hole is formed in the water tank, and a drain valve is arranged in the drain hole; the water level control device in sleeved connection with the drain valve is arranged in the steam generating chamber, the water level control device comprises a limiting hood opened in the peripheral wall, a water outlet is formed in the top of the limiting hood, and a floating block is arranged in the limiting hood; a leak hole plug is arranged at the water outlet, and the bottom of the leak hole plug is a part in contact with the floating block; the floating block shifts up and down in the limiting hood along with change of the water level; when the floating block is in contact with the drain hole plug, the water outlet is plugged to stop draining; otherwise, the floating block is separated from the leak hole plug, and the water outlet is opened to supplement water. The water control device disclosed by the invention is simple in structure and small in occupied space, is immediately triggered to control water supplementation for the steam generating chamber, and is electric energy-saving, and the condition that the humidifier is likely to overflow or dry out is effectively avoided, so that a user can use the humidifier safely.