The invention discloses a direct-expansion solar heat pump and sewage source heat pump coupling heat supply system. The direct-expansion solar heat pump and sewage source heat pump coupling heat supply system is characterized in that a direct-expansion solar heat pump system body enables the evaporation temperature of refrigerants to be maintained within a certain range by arranging a phase change heat storage device, and accordingly the influence of the change of solar radiation intensity on the system stability is greatly reduced; a heat storage water tank stores solar energy and preheats intermediary water, so that heat produced by the direct-expansion solar heat pump system body is effectively transmitted to a heat consumer, and effective coupling of solar heat collection, the heat storage technology and a sewage source heat pump is completed. The direct-expansion solar heat pump and sewage source heat pump coupling heat supply system has the benefits and effects that the problems of intermittency and unstability of solar energy resources are effectively solved, the effect that the system can supply energy is ensured, the system performance is improved substantially, and the system is efficient and environmentally friendly.