A data writing method, a memory control circuit unit and a memory storage apparatus are provided. The method includes: receiving a first write command and first data corresponding to the first write command, and writing the first data into a third physical erasing unit in first physical erasing units; and if a usage frequency of a fourth physical erasing unit in the first physical erasing units is less than a predetermined value, performing a data arrangement operation corresponding to the first write command to copy second data stored by the fourth physical to at least one of second physical erasing units.