The invention discloses a three-network convergence-oriented digital home network service management system and a three-network convergence-oriented digital home network service management method, which are used for providing undifferentiated service for a user screen. The management system consists of a safety management subsystem, a control subsystem, a service management subsystem, an external network access subsystem and an application domain network access subsystem; the system uniformly manages various applications provided by a digital home in a service mode and provides basic service management functions such as service query, order, use and the like for a user, so that the expandability, the configurability, the operability and the manageability of digital home network service are enhanced; meanwhile, the system is expanded and improved on the basis that the conventional service management system only supports the Internet service so as to support three heterogeneous networks, namely a computer network, a telecommunication network and a broadcast television network, and effectively overcome the defect that the services of the heterogeneous networks are difficult to converge; and a home gateway provides a uniform service interface for the user, so that the difference of underlying communication technology among different networks is shielded; therefore, the process of using the service by the user is clearer and simpler.