The invention discloses a method and a system for multiplexing data buffer regions. The method comprises the following steps: dividing a preset number of regions from a free region of an RAM as data buffer regions by employing preset capacity as a unit; storing all data buffer regions into a waiting queue; when receiving a bus read-write data buffer request of a protocol layer, distributing the data buffer regions in the waiting queue for carrying out bus read-write data buffering according to the bus read-write data buffer request; transferring the data buffer regions finishing the bus read-write data buffer request into a free queue; and when receiving a data temporary storage request of a logic layer, distributing the data buffer regions in the free queue to store temporary data. The data received and transmitted on a cache bus of the free region of the RAM can be used in the data read-write process; when the bus waits a response or is free, the free region of the RAM is used for storing the temporary data in background processing; the data scheduling frequency can be reduced by multiplexing of the region; and the effect velocity of an instruction is improved.