The embodiment of the invention provides a waste heat heating system for a data center. The waste heat heating system comprise a high-temperature heat pump, a water chilling unit and a conventional heat pump; an evaporator of the high-temperature heat pump absorbs heat of heating network return water to decrease the temperature of the heating network return water; the water chilling unit utilizeswaste heat of refrigerated circulating water in the data center to conduct first-time heating on the heating network return water output by the evaporator side of the high-temperature heat pump; the conventional heat pump is used for conducting second-time heating on the heating network return water output by the water chilling unit; and a condenser of the high-temperature heat pump is used for conducting third-time heating on the heating network return water output by the conventional heat pump, and the heating network return water is heated up to the preset heat supplying temperature and then provided. According to the waste heat heating system, the temperature of the heating network return water is actively decreased on the heat source side, and the waste heat recovery utilization rateof the data center is increased; the temperature difference between supplied water and the return water is increased, the temperature of the heating network supplied water is increased, the external heat supplying capability is improved, and energy consumption for transmission and distribution is lowered; and cold-heat supplying is achieved, and thus the energy utilization efficiency is improved.