The invention discloses a heating control method for constant pressure gas blending coke oven, and belongs to the technical field of coke oven heating control method. The method is used to carry out automatic control on coke oven blending heating. The technical scheme comprises the following steps: on-line monitoring the coke oven main pressure, the blast furnace gas flow, the flow of coke oven gas for blending, and the flue suction force; establishing a mathematic formula for calculating the coke oven gas blending flow, calculating the mixing amount of coke oven gas according to the measured data; establishing a mathematic formula for calculating the blast furnace gas flow, calculating the set flow of the blast furnace gas according to the flow of the mixed coke oven gas; establishing a mathematic formula for calculating the sub-flue suction force, and calculating the suction force set values of the machine side sub-flue and the coke side sub-flue of the coke oven according to the percentage of the mixed coke oven gas in the blast furnace gas. The method can adjust the coke oven gas blending amount according to the gas main pressure and the calculation formula, thus the automatic blending heating of coke oven gas is achieved, moreover, the phenomenon of gas dissipation due to the gas overpressure in the pipe network is effectively relieved and at the same time the normal production of coke oven is not affected.