WEAR LEVELING METHOD, MEMORY CONTROL CIRCUIT UNIT AND MEMORY STORAGE DEVICE

A wear leveling method, a memory control circuit unit and a memory storage device are provided. The method includes: selecting a first physical erasing unit from physical erasing units not stored with valid data according to erase counts, and selecting a second physical erasing unit having a valid data amount being less than a capacity of one physical erasing unit from the physical erasing units stored with the valid data. The method also includes: selecting a third physical erasing unit having the valid data amount being less than the capacity of one physical erasing unit from the physical erasing units storing valid data according to the erase counts. The method further includes: writing the valid data of the second physical erasing unit and at least part of the valid data of the third physical erasing unit into the first physical erasing unit.