Embodiments of the present invention disclose a channel decoding method, apparatus, and system. The channel decoding apparatus includes a memory storing instructions; and a processor coupled to the memory to execute the instructions to: obtain decoding information of first channel decoding of a data block; determine whether the first channel decoding fails; in response to determining that the first channel decoding fails, obtain a reference sequence number of the data block; obtain at least one matching historical demodulated soft value; combine the demodulated soft value of the data block and the at least one matching historical demodulated soft value to obtain a combined demodulated soft value of the data block; and perform second channel decoding on the combined demodulated soft value of the data block.