The invention discloses a system for high-efficiency utilization of low-quality waste heat. The system for the high-efficiency utilization of the low-quality waste heat comprises a waste heat recoverysystem and a circulating system, wherein the waste heat recovery system comprises an evaporator, a waste heat inlet pipe, a waste heat outlet pipe and a filtering device; and the circulating system comprises an organic working medium pipeline, a gas storage tank, a condenser, a liquid storage tank, a condensate pump, a liquid replenishing pump, flow dividing control valves, a Roots power machine,a gas storage tank sensor group, a gas inlet sensor group, a gas outlet sensor group and liquid replenishing flowmeters. According to the system for the high-efficiency utilization of the low-qualitywaste heat, low-quality waste heat gas is used as a heat source, an organic working medium is used as a circulating working medium, the waste heat recovery system enables the liquid organic working medium to absorb heat from the waste heat gas and convert the heat into a gaseous state, the steam of the organic working medium enters the Roots power machine to push the Roots power machine to do work, heat energy is converted into mechanical energy, and then the steam of the organic working medium is condensed into the liquid state through the condenser and is continuously recycled. The system for the high-efficiency utilization of the low-quality waste heat achieves recycling of the low-quality waste heat, and is simple in structure, high in energy utilization rate and high in heat conversion efficiency.