To address the disadvantage of the “path-splitting selecting strategy based on a search set under a successive cancellation list” decoding algorithm, a path-splitting strategy based on a reliability function and a pruning strategy relying on an auxiliary path metric (APM) are proposed. Subsequently, a path-splitting selecting strategy based on a reliability function under a successive cancellation list (PSS-RF-SCL) decoding algorithm is proposed. During the decoding of the algorithm, the path metric (PM) values for all paths is calculated before performing path splitting on each information bit. The reliability function value of the bit is calculated using these PM values. Information bits with reliability-function values below its average value (namely, the threshold α) are regarded as bits that require path splitting. This method is used to identify splitting bits and significantly reduces the splitting number. Additionally, paths with APM values above the APM average value (namely, the threshold β) of the correct decoding path are considered unreliable paths. Pruning the unreliable paths significantly reduces the total number of decoding lists. Simulation results show that compared with conventional path-splitting decoding algorithms based on search sets, the proposed PSS-RF-SCL decoding algorithm significantly reduces the decoding complexity without performance loss.