The invention relates to a system for forwarding messages of an ESB. The system comprises an access engine and an ESB kernel, wherein the access engine provides access support of respective technical specification for a caller party and a callee party, and forwards a call request of the caller party or an execution result of the callee party; and the ESB kernel determines positions and types of afirst access engine corresponding to the caller party and a second access engine corresponding to the callee party, and selects direct forwarding, forwarding after natural serialization or forwardingor after unified message conversion of the call request transmitted by the caller party through the first access engine according to a determination result. The invention also relates to an ESB message forwarding method and a server which correspond to the system. The method and the system thereof perform message conversion of different strategies aiming at different conditions on comparison of the access engine types on the ESB, execute direct forwarding, natural serialization or unified message conversion of the messages according to different priorities, and achieve the aims of reducing message conversion times and improving the performance through optimization.