An embodiment of the present invention relates to a method for expanding a PCIe
bus region, capable of allocating
configuration space address to a PCIe device of an expanded region from
memory address of an endpoint device of a
root complex, establishing a corresponding relationship between the
configuration space address and
bus number / device number / function number (BDF), and allocating a
bus number to the PCIe device found in the expanded region from a second bus
assembly of the expanded region, wherein the bus number is used for determining the BDF of the PCIe device found in the expanded region, so that a
configuration space register of the PCIe device found in the expanded region can be accessed through the BDF of the PCIe device found in the expanded region according to the corresponding relationship between the configuration space address and the BDF, in this way, expansion of the PCIe bus region is achieved, and the problem that expansion of the PCIe bus region cannot be performed in the prior art is solved, thus the number of the PCIe devices in a
system cannot be limited by 256 buses.