Abstract: The CHP heating system, which takes the power plant circulating water as the low temperature heat source of heat pump, makes use of the compressing heat pump with electricity-driven or absorbing heat pump with absorption steam to absorb energy from the circulating water. The electrical and thermal income will be impacted simultaneously by the adjustment of cold end. In the view of maximum economic net income, the cold end system optimization is conducted for this CHP system. The mathematical model for every segment of the system are established and solved. At last, based on a certain 600MW unit and compressing heat pump, the system optimization for four heating area between 2, 000, 000 to 8, 000, 000 square meter is carried on. Its concluded that the best inlet temperature always rise, the calculation ratio increase firstly and decrease to the minimum and the best overall income is less than the heat pump income. In the practical operation, the best parameters should be most closed to the theoretical optimum under the situation that the condenser vacuum is not less than the minimum value.