The power plant boiler high temperature slag is typically the use of recycled water for cooling the slag, and recycled water slag wasted heat into the cooling tower and the atmosphere. Not only the heat of the slag has not been fully utilized, but also the boiler thermal efficiency and recycled water evaporation were caused by the waste of water resources to a certain extent, and by thermal pollution on the environment. It is very important that Boiler high temperature slag wasted heat recovery for energy conservation, and improved the overall boiler thermal efficiency. The design of the works of three waste heat recovery scheme, the effect of energy saving and economic benefits of each program optimization calculation resulted in cold slag recycling power plant boiler and high temperature slag wasting heat for heating boiler feed water, the cold residue machine released hot water into the low temperature heater between 7# and 8#, there are very significant results and thus reduce the turbine extraction, reduce the turbine power heat rate, and improve the efficiency of the entire power plant power generation. Its findings can be generalized to other power plant boilers and lowtemperature waste heat recycling.