The invention discloses a processing method, apparatus, and system for TCP connection. The method comprises: a connection message that is sent by a client and is used for establishing TCP connection with a server side is received; a message type of the received connection message is determined, wherein the message types of connection messages at least include a synchronization message and a response message; when the message type of the connection message is the response message type, the response message is verified by using connection verification information, wherein the connection verification information is generated based on a synchronization message; and when the response message verification is done successfully, the response message is forwarded to the server side. Therefore, technical problems that the protection performance is poor and the connection response is delayed because connection needs to be established again after the TCP connection message sent by the client is verified can be solved.