The invention discloses an RCM-based thermal power unit equipment maintenance method comprising the following steps of A, constructing a hierarchical equipment asset structure tree, and structurally decomposing and layering each piece of the equipment for storage; B, constructing a complete fault knowledge base, analyzing multiple information, and extracting various fault data to constitute a knowledge base; C, constructing a fault probability model by using a maximum likelihood method; D, calculating a reliability index according to the fault probability function; E, formulating a risk matrixevaluation standard as the risk assessment method of the RCM-based equipment maintenance system; and F, screening optimization strategies to assist engineers in scientific decision-making. The methodprovided by the invention introduces the reliability-centered maintenance concept into the maintenance decision of the power plant based on the current maintenance status of the main equipment of thethermal power plant, thereby improving the reliability and availability of the equipment, or reducing the maintenance cost.