Exemplary embodiments of the disclosure provide a memory management method for a rewritable non-volatile memory module including the following steps. A host write operation is performed to receive a write command from a host system and store a first data corresponding to the write command to a first physical unit. A first updating data corresponding to the host write operation is recorded. A data merge operation is performed to read a second data from a second physical unit and store the second data to a third physical unit. A second updating data corresponding to the data merge operation is recorded. A management information is read from the rewritable non-volatile memory module to a buffer memory and updated in the buffer memory according to the first updating data and the second updating data.