A flash memory storage apparatus including a multi level cell (MLC) NAND flash memory, a flash memory controller, and a host transmission bus is provided. The MLC NAND flash memory includes a plurality of blocks for storing data, wherein each of the blocks has an upper page and a lower page, and the writing speed of the lower page is faster than that of the upper page. The flash memory controller is electrically connected to the MLC NAND flash memory and is used for executing storage mode switching steps. The host transmission bus is electrically connected to the flash memory controller and is used for communicating with a host. The flash memory storage apparatus provided by the present invention can provide multiple storage modes in order to store different data.