Abstract: Aiming at the circulating fluidized bed boiler burning high volatile and high calorific value coal, through the adjustment of the boiler running oxygen, the ratio of primary and secondary air, the bed pressure and the ratio of upper and lower secondary air, the influence law of the change of a single factor in boiler operation on the boiler combustion efficiency was obtained. Through the combination of optimal variable operating conditions, the content of fly ash fuel was reduced and the boiler efficiency was improved. The test results show that under 370 and 430 t/h conditions, the combustible content of fly ash after adjustment is reduced by 1.44% and 0.69%, and the combustible content of slag after adjustment is reduced by 0.26% and 0.14% compared with that before adjustment. After adjustment, the boiler efficiency increased by 0.77% and 0.42% compared with that before adjustment.