A message processing method based on the SIP Protocol for a message processing system including a number of application servers, core network devices of a core network and a SIP proxy server, the method comprising: step (i). processing, by the SIP proxy server SIP messages received from the core network to judge and distribute the received SIP messages to corresponding application servers for processing, wherein the SIP proxy server is a uniform access interface for the SIP messages received by the processing system from the core network; step (ii). processing, by the SIP proxy server, SIP messages received from the application servers to distribute, according to instructions from the application servers, the received SIP messages to corresponding core network devices for processing, wherein the SIP proxy server is a uniform access interface for the SIP messages received by the processing system from the application servers; wherein the step (i) further comprises a step of judging whether a to-header in the message contains a tag parameter, and whether the message is a request message, if the to-header in the message does not contain a tag parameter and the message is a request message, the SIP proxy server distributes the message to a corresponding application server according to a pre-configured message distribution strategy, and simultaneously adds a sign indicating which core network device the message is from at the end of the message, and if the to-header in the message contains a tag parameter or the message is a response message, a further step is taken to judge whether the tag parameter in the to-header in the message contains identification information of the application server to which the message is to be distributed. step (i). processing, by the SIP proxy server SIP messages received from the core network to judge and distribute the received SIP messages to corresponding application servers for processing, wherein the SIP proxy server is a uniform access interface for the SIP messages received by the processing system from the core network; step (ii). processing, by the SIP proxy server, SIP messages received from the application servers to distribute, according to instructions from the application servers, the received SIP messages to corresponding core network devices for processing, wherein the SIP proxy server is a uniform access interface for the SIP messages received by the processing system from the application servers; wherein the step (i) further comprises a step of judging whether a to-header in the message contains a tag parameter, and whether the message is a request message, if the to-header in the message does not contain a tag parameter and the message is a request message, the SIP proxy server distributes the message to a corresponding application server according to a pre-configured message distribution strategy, and simultaneously adds a sign indicating which core network device the message is from at the end of the message, and if the to-header in the message contains a tag parameter or the message is a response message, a further step is taken to judge whether the tag parameter in the to-header in the message contains identification information of the application server to which the message is to be distributed.