A control method of a flash memory controller, wherein the control method includes the steps of: when data is written to a page of any block of a flash memory module, recording a write time in the page; create a write time table, wherein the write time table records block numbers of blocks having data written therein and corresponding write time; compress the write time table to generate a compressed write time table, wherein the compressed write time table contains multiple time ranges and corresponding indexes, each index corresponds to a page of the flash memory module, and the page records block numbers of all blocks whose writing time is within the corresponding time range.