The invention relates to an energy saving amount determination method for recycling waste heat of circulating cooling water by means of a heat pump. The method includes the step (1) of determining the amount of waste heat absorbed by the heat pump from circulating cooling water of a condenser, the step (2) of determining the decreased amount of unit electricity generation power after pressure of the condenser is improved, and the step (3) of determining the energy saving amount of waste heat generated when the heat pump is utilized to recycle circulating cooling water of the condenser. The heat pump is used for recycling waste heat of circulating cooling water of the condenser to heat circulating water of a heating network, losses of a cold source of a steam turbine are reduced, external heating loads are increased, consumption of fire coal is reduced, and the purpose of energy saving is achieved. The energy saving amount of waste heat, recycled by the heat pump, of circulating cooling water of the condenser is calculated successfully by means of system analysis, the through is rigorous, calculation is scientific, and the method has great significance in improvement on recovery efficiency of waste heat and the waste heat recovery process.