Disclosed is an air-fuel ratio control boiler using a air pressure sensor and method for controlling the air-fuel ratio thereof. The boiler is comprised of a fan, the air pressure sensor, a air pressure sensor voltage measurement unit, a air pressure sensor voltage compensation unit, and a controller, and previously compensates for noise factors caused by deviation (error) of a component property, a constituent, of the air pressure sensor so as to be matched to initial reference voltage prior to operating the fan, thereby maximizing the effectiveness of the air-fuel ratio. Further, the boiler makes it possible not only to exert an optimal fuel efficiency effect due to the maximization of combustion efficiency, but also to minimize discharge of harmful gases, thereby preventing environmental pollution in advance, and thus improving the reliability of products.