The present invention provides a control method of a flash memory controller is disclosed, wherein the flash memory controller is configured to access a flash memory module, and the control method comprising: allocating a memory space within a memory for storing data from the host device; dividing the memory space into a plurality of zone buffers, wherein each of the zone buffers is used to store data corresponding to one zone having an opened state; and for a first zone buffer of the plurality of zone buffers, controlling a first buffer and a second buffer within the first zone buffer to alternately store data of a first zone from the host device and write the data of the first zone to a zoned namespace of the flash memory module.