With the development of network security research, network attack modeling and analysis techniques have been paid more and more attention. A Generalized Stochastic Colored Petri Net (GSCPN) Model is proposed. To each attack, a GSCPN model is constructed to describe the relation of components graphically. Algorithm to construct a composite attack and method for network vulnerability analysis are delivered also. The exploitation cost of vulnerabilities is estimated. The method is relatively simple, which is different from traditional method. The network example further validates the proposed method for network vulnerability analysis.