The invention discloses a boiler water level control device which comprises a water supply pump, a water supply adjusting valve, a steam adjusting valve, an electrode chamber and a water supply pump control system. The water supply pump control system comprises a first replay and a contactor for controlling the water supply pump, a reserve water pump is further included, the steam adjusting valveis connected with a steam flow transmitter, the steam flow transmitter is connected with a pneumatic calculator, the electrode chamber is connected with a water level pressure difference transmitter,a signal of the pneumatic calculator and the water level pressure difference transmitter are connected with a voltage comparator in parallel, a signal of the voltage comparator is transmitted to a regulator, a signal of the regulator is transmitted to the water supply adjusting valve, the reserve water pump is controlled by a magnet switch, the magnet switch is arranged at the output end of a pneumatic diaphragm control valve, and the pneumatic diaphragm control valve is connected with the steam adjusting valve through a pipe. By means of the device, the steam pressure and the boiler water level are comprehensively compared, the boiler water level adjusting is more close to actual conditions, and the influences of water level virtual increase during excessive steam using can be removed.