A switching system, comprising a first switching device and a second switching device, wherein the first switching device and the second switching device are connected by using a network; the first switching device comprises: multiple Peripheral Component Interconnect Express, PCIe, upstream ports, configured to connect to at least one host; the second switching device comprises: at least one PCIe downstream port, configured to connect to at least one input/output, I/O, device; and the second switching device is configured to: receive a first data packet transmitted by the first switching device by using the network, convert the first data packet to a second data packet complying with a PCIe protocol, and transmit the second data packet to a target I/O device of the second data packet; wherein the second switching device further comprises: a first internal processing apparatus, connected to the at least one PCIe downstream port by using an internal connection line of the second switching device, wherein the first internal processing apparatus is configured to determine at least one I/O device connected to the second switching device by using the at least one PCIe downstream port and obtain information of the at least one I/O device connected to the second switching device, the information comprising at least one of a Bus Device Function, BDF, and a topology structure; and the first internal processing apparatus is further configured to convert the first data packet to the second data packet complying with the PCIe protocol. multiple Peripheral Component Interconnect Express, PCIe, upstream ports, configured to connect to at least one host; the second switching device comprises: at least one PCIe downstream port, configured to connect to at least one input/output, I/O, device; and the second switching device is configured to: receive a first data packet transmitted by the first switching device by using the network, convert the first data packet to a second data packet complying with a PCIe protocol, and transmit the second data packet to a target I/O device of the second data packet; wherein the second switching device further comprises: a first internal processing apparatus, connected to the at least one PCIe downstream port by using an internal connection line of the second switching device, wherein the first internal processing apparatus is configured to determine at least one I/O device connected to the second switching device by using the at least one PCIe downstream port and obtain information of the at least one I/O device connected to the second switching device, the information comprising at least one of a Bus Device Function, BDF, and a topology structure; and the first internal processing apparatus is further configured to convert the first data packet to the second data packet complying with the PCIe protocol. at least one PCIe downstream port, configured to connect to at least one input/output, I/O, device; and the second switching device is configured to: receive a first data packet transmitted by the first switching device by using the network, convert the first data packet to a second data packet complying with a PCIe protocol, and transmit the second data packet to a target I/O device of the second data packet; wherein the second switching device further comprises: a first internal processing apparatus, connected to the at least one PCIe downstream port by using an internal connection line of the second switching device, wherein the first internal processing apparatus is configured to determine at least one I/O device connected to the second switching device by using the at least one PCIe downstream port and obtain information of the at least one I/O device connected to the second switching device, the information comprising at least one of a Bus Device Function, BDF, and a topology structure; and the first internal processing apparatus is further configured to convert the first data packet to the second data packet complying with the PCIe protocol. receive a first data packet transmitted by the first switching device by using the network, convert the first data packet to a second data packet complying with a PCIe protocol, and transmit the second data packet to a target I/O device of the second data packet; wherein the second switching device further comprises: a first internal processing apparatus, connected to the at least one PCIe downstream port by using an internal connection line of the second switching device, wherein the first internal processing apparatus is configured to determine at least one I/O device connected to the second switching device by using the at least one PCIe downstream port and obtain information of the at least one I/O device connected to the second switching device, the information comprising at least one of a Bus Device Function, BDF, and a topology structure; and the first internal processing apparatus is further configured to convert the first data packet to the second data packet complying with the PCIe protocol.