Abstract: A concept model of the security service platform is put forward which is used to support the service capability opening in next generation network（NGN）. Based on the model, a number of key issues are discussed, such as the security services provided in security service layer, the object model of security service components in distributed function layer and the functional entities in distributed function layer. Furthermore, two kinds of architectures of the security service platform are provided based on the transverse and vertical security service models individually.

Key words: next generation network, security service, opening service capability, concept model