This study was performed to effectively use a combustion control system of coke oven battery by estimating the required coke heat quantities of mixed coals from coke heat quantities of individual coals. The coke heat quantities for 29 different coals and mixed coals blending 2-20% of individual coals of 10-11 types were measured by the apparatus using double heater which could minimize surface heat loss. The multiplication of coke heat quantities of individual coals by mixing ratios was considerably different from actual measured coke heat quantities of mixed coals. To estimate the coke heat quantities of mixed coals, the calculation by estimating equation that is expressed as a function of coke heat quantities of individual coals, mixing ratios and weighting factor was in good agreement with real measured values.