A read voltage setting method for a rewritable non-volatile memory module is provided. The method includes: reading test data stored in memory cells of a word line to obtain a corresponding critical voltage distribution and identifying a default read voltage corresponding to the word line based on the corresponding critical voltage distribution; applying a plurality of test read voltages obtained according to the default read voltage to the word line to read a plurality of test page data; and determining an optimized read voltage corresponding to the word line according to the minimum error bit number among a plurality of error bit numbers of the test page data. The method further includes calculating a difference value between the default read voltage and the optimized read voltage as a read voltage adjustment value corresponding to the word line and recording the read voltage adjustment value in a retry table.