Waste heat recovery for heating is an important means to realize energy saving, emission reduction and clean heating. The effect of low return water temperature of heating network on waste heat recovery rate for the steel plant has been quantitatively analyzed in this paper. A waste heat recovery system for heating by reducing return water temperature has been also developed. The principles have been proposed to guide how to determine the internal heat exchange networks in each waste heat recovery unit. The equivalent COP of the novel waste heat recovery heating system has been introduced as the performance index. The whole low-grade waste heat recovery heating process has been exemplified in a particular case study and its economic character has been analyzed in detail. The results show that if the return water temperature of heating network decreases to 15℃, the low-grade waste heat recovery rate of the steel plant would reach up to 100%, and the equivalent COP would be 6.1. Utilizing the waste heat recovery heating system increases the heating capacity of the primary heating network up to 798 MW. The static payback period of the waste heat recovery heating system for steel plant is 4 years, so it has good economic benefits.