A protocol conversion method, wherein the method comprises: implementing, by a protocol conversion apparatus, frequency synchronization and time synchronization with a baseband unit, BBU, by using the Ethernet protocol; obtaining, by the protocol conversion apparatus, frequency synchronization information and time synchronization information from an Ethernet interface; converting, by the protocol conversion apparatus, the frequency synchronization information and the time synchronization information into frequency synchronization information and time synchronization information that are in a common public radio interface, CPRI, protocol format; and sending, by the protocol conversion apparatus, the converted frequency synchronization information and time synchronization information to a remote radio unit, RRU, by using a CPRI interface, wherein the RRU supports the CPRI protocol; wherein the method further comprises: when a slow control and management channel exists between the protocol conversion apparatus and the RRU, allocating, by the protocol conversion apparatus, a high-level data link control, HDLC, address to the RRU; initiating, by the protocol conversion apparatus, a dynamic host configuration protocol, DHCP, request on behalf of the RRU to obtain an Internet Protocol, IP, address of the RRU, and establishing a mapping relationship between the IP address and the HDLC address; and identifying, by the protocol conversion apparatus according to the mapping relationship between the IP address and the HDLC address, a control and management packet sent by the BBU to the RRU, converting the control and management packet into an HDLC packet, encapsulating the HDLC packet into a CPRI frame, and sending the CPRI frame to the RRU. implementing, by a protocol conversion apparatus, frequency synchronization and time synchronization with a baseband unit, BBU, by using the Ethernet protocol; obtaining, by the protocol conversion apparatus, frequency synchronization information and time synchronization information from an Ethernet interface; converting, by the protocol conversion apparatus, the frequency synchronization information and the time synchronization information into frequency synchronization information and time synchronization information that are in a common public radio interface, CPRI, protocol format; and sending, by the protocol conversion apparatus, the converted frequency synchronization information and time synchronization information to a remote radio unit, RRU, by using a CPRI interface, wherein the RRU supports the CPRI protocol; when a slow control and management channel exists between the protocol conversion apparatus and the RRU, allocating, by the protocol conversion apparatus, a high-level data link control, HDLC, address to the RRU; initiating, by the protocol conversion apparatus, a dynamic host configuration protocol, DHCP, request on behalf of the RRU to obtain an Internet Protocol, IP, address of the RRU, and establishing a mapping relationship between the IP address and the HDLC address; and identifying, by the protocol conversion apparatus according to the mapping relationship between the IP address and the HDLC address, a control and management packet sent by the BBU to the RRU, converting the control and management packet into an HDLC packet, encapsulating the HDLC packet into a CPRI frame, and sending the CPRI frame to the RRU.