An improved Reed–Solomon (RS)-polar code concatenation scheme with a threshold is proposed. It applies successive cancellation list and hard-decision decoding based on the low-complexity chase algorithm. A new multiplicity assignment module is proposed to make it possible to realize the RS-polar code concatenation and facilitate hardware decoder design. The proposed scheme achieves high decoding performance, low decoding complexity, and short latency. The simulation results show that the improved concatenation scheme gives a coding gain reaching about 0.4 dB compared with the traditional RS-polar scheme. Moreover, it can reduce the average number of RS codewords to be decoded in a concatenated code by 65% and decrease the decoding latency by 50% when the signal-to-noise ratio is 1.75 dB.