A memory management method and a storage controller using the same are provided. The method includes reading a target word-line to identify a plurality of raw Gray code indexes corresponding to a plurality of memory cells of the target word-line; performing a decoding operation on raw data of the target word-line to identify a plurality of decoded Gray code indexes corresponding to the memory cells; calculating a plurality of Gray code absolute bias values corresponding to the memory cells according to the raw Gray code indexes and the decoded Gray code indexes; and identifying one or more abnormal memory cells among the memory cells according to the Gray code absolute bias values; and recording the one or more abnormal memory cells into an abnormal memory cell table, wherein a Gray code absolute bias value of each of the one or more abnormal memory cells is greater than a bias threshold.