The invention relates to the field of multi-fuel mixed combustion generating set, especially to a method for optimized distribution of the loads of a multi-fuel mixed combustion generating set. The method includes fitting coal consumption characteristic curve according to the coal consumption characteristic parameters of the generating set, distributing total generated power in combination with the equal incremental rate criterion, taking limiting values for over-limited cases, and redistributing remaining power to residual unit sets. The operation can be repeated until the loads of all sets are within constrained conditions, and the optimized load distribution results for all unit sets can be finally obtained. The method helps an operator to obtain optimal load distribution result, when the operator knows the total generating power and total BFG amount. The coal consumption rate of a thermal power set can be reduced. The method is meaningful for national energy saving and emission reduction policy.