A new network protocol (DemandPriority Protocol) environment can provide more satisfying service fordifferent urgent transmission requests. In this paper, in order toprovide guidance for the selection of environment of multimedia datatransmission in Computer Supported Cooperative Work better, anobject-oriented protocol specification language based on C++ is used todesign a virtual environment of multiworkstation of computer cooperativework and to simulate exe-cution of demand priority network protocoland then the performances of various transmission requests are analyzed.Finally, an evaluation of the demand priority LAN is given.