The planning and the optimization of biomass thermal power are directly related to the economic operation, biomass resource utilization and environmental protection. On the basis of establishing an index system for the evaluation of site selection for biomass thermal power plants, the rough set method was applied to obtain the index weights based on potential information of the system. Through decision-making of experts, the quantitative and qualitative information was integrated, and then the priority of the alternative locations was obtained. The multi-objective optimal model for the planning and optimization of the biomass thermal power plant was built up to balance the economical efficiency and the average comprehensive efficiency. In consideration of decision-maker’s predilection and heat load demand, the goals of cost minimization and average comprehensive efficiency maximization were achieved at the same time, and the plant scale and heating scheduling optimization scheme were obtained. The numeric example indicated that the method for the planning and optimization of the biomass thermal power plant is scientific and practical.