The invention relates to a technique for recombining, replacing, compressing and encapsulating network communication messages, in particular to a wide area network VPN accelerating gateway and its accelerating communication system and method. The WAN VPN acceleration gateway is: network protocol stack, IPSec and Internet key exchange protocol module, TCP agent and tunnel module and network protocol stack call in turn to form a closed-loop system, while TCP agent and tunnel module call the application package library module one-way Functions provided; ACK proxy module, package/data label cache/compression module, IPSec and Internet key exchange protocol modules are called sequentially, while package package/data label cache/compression module calls data label cache library one-way function function. The invention reduces the transmission of repeated data, greatly improves the link data transmission rate, and greatly enhances the high speed and reliability of the network.