The invention discloses an automatic control boiler system which comprises a monitoring diagnosis controller and a boiler. The boiler comprises a pollution discharge pipe arranged at the lower end of a boiler steam pocket. The pollution discharge pipe is provided with a blow-down valve. One end of the blow-down valve is connected with a valve adjusting device. The valve adjusting device is in data connection with the monitoring diagnosis controller, so that valve opening data are transmitted to the monitoring diagnosis controller, meanwhile, an instruction is received from the monitoring diagnosis controller, and the opening of the blow-down valve is adjusted. The steam pocket further comprises a water quality analyzer. The water quality analyzer comprises a PH value measuring unit so as to measure the PH value of water in the steam pocket. The water quality analyzer is in data connection with the monitoring diagnosis controller so as to obtain measured PH data. The boiler discharges pollution at regular intervals, the pollution discharge speed is kept constant, a central diagnosis monitor automatically sets pollution discharge time according to the measured PH value, and therefore the pollution discharge amount is automatically controlled. Since pollution time is automatically calculated, compared with the prior art, hysteresis is reduced, and optimal pollution discharge control can be achieved.