Wear leveling method of non-volatile memory

A wear leveling method, applied to a non-volatile memory containing a plurality of blocks, comprising steps of:

• assigning the blocks to either a first group, a second group, or a third group according to the corresponding history numbers and data stored in the blocks, wherein the history number indicates an absolute time of writing data into the corresponding block, the first group contains N erased blocks with relatively high history numbers, the second group contains M erased blocks with relatively low history numbers, and the third group contains the remaining blocks not either assigned to the first group or the second group;
• calculating an average history number of the non-volatile memory;
• selecting a first block containing a clod data from the third group;
• selecting a second block from the first group;
• copying the cold data from the first block into the second block, and updating the history number of the second block according to the absolute time of writing the cold data into the second block;
• and
• erasing the first block.