A decoding method, a memory storage device and a memory controlling circuit are provided. The decoding method includes: sending a read command sequence configured to read the memory cells, so as to obtain a plurality of first verification bits; executing a first decoding procedure according to the first verification bits, and determining whether a first valid codeword is generated; if the first valid codeword is not generated, sending another read command sequence configured to obtain a plurality of second verification bits; calculating a total number of the memory cells conforming to a specific condition according to the second verification bits; obtaining a channel reliability message according to the total number; and executing a second decoding procedure according to the channel reliability message. Accordingly, a correcting ability of decoding may be improved.