A method for programming data is provided for a memory storage device having a rewritable non-volatile memory module and a buffer memory. The method includes receiving a plurality of data including a first-type data and at least one second-type data, and a size of the first-type data is smaller than a data size threshold. The method includes temporarily storing the plurality of data into the buffer memory, and programming the first-type data and at least one part of the at least one second-type data stored in the buffer memory into a physical program unit set if it is determined that the plurality of data are complied with a predetermined condition. The method includes obtaining writing statuses of the first-type data and the at least one part of the at least one second-type data at the same time.