The invention discloses an efficient low-grade residual heat resource utilization system for a coal-fired power plant. The system comprises an air preheater, a secondary fan, a low-temperature economizer, a dry electric precipitator, a first induced draft fan, a circulating medium heating module, a desulfurization tower and a chimney, which are sequentially communicated, and also comprises a low low-temperature economizer, a wet electric precipitator and a second induced draft fan, which are sequentially communicated, wherein a flue gas outlet of the secondary induced draft fan is communicated with the desulfurization tower, and a heat exchanger of the low low-temperature economizer is communicated with a coolant of the circulating medium heating module. The system further comprises an air heater arranged between the secondary fan and an air inlet of the air preheater, wherein a heat exchanger of the air heater is communicated with a heating medium of the circulating medium heating module; the heating medium of the circulating medium heating module is used for heating the coolant through the heater. According to the efficient low-grade residual heat resource utilization system for the coal-fired power plant, a residual heat resource utilization manner is optimized to improve the overall energy efficiency level of a unit according to the principle of temperature equivalence and step utilization.