The invention provides an automatic temperature control method and system of a fluidized bed combustion boiler. The method comprises the steps of measuring oxygen content of discharged flue gas under the working condition, receiving the oxygen content and the set temperature needed by the operation of the fluidized bed combustion boiler through a control device and adjusting coal feed quantity of a coal feeder, air quantity of an air blower and air quantity of an induced draft fan through the control device according to the oxygen content, the needed temperature, the real temperature, the pressure of an air box and the internal pressure of a hearth. According to the automatic temperature control method and system of the fluidized bed combustion boiler, the coal feed quantity of the coal feeder can be measured accurately, therefore, the coal feeder, the air blower and the induced draft fan are controlled automatically, and the purpose of automatically controlling the temperature of the fluidized bed combustion boiler is achieved. By means of the automatic temperature control method and system of the fluidized bed combustion boiler, the burning quality of the fluidized bed combustion boiler can be improved, and the failure rate of the fluidized bed combustion boiler is reduced.