The invention discloses a set-top-box-based triple play system, which comprises one or more than one terminal, a set-top box and a service publication platform. Different terminals acquire service published by the service publication platform from different networks through the set-top box. The system is characterized in that the set-top box comprises a terminal type detection module, a network type detection module and a service fusion module, wherein the terminal type detection module is used for detecting and identifying the types of the terminals connected to the set-top box; the network type detection module is used for detecting the types of available networks, selecting one from the available networks as an interaction network for the terminals and the service publication platform, and identifying the types of the networks used for the terminals or the service publication platform to transmit requests; and the service fusion module is used for disintegrating a web services description language (WSDL) from the service publication platform, selecting proper sub-WSDLs according to detection results of the terminal type detection module and the network type detection module, combining the sub-WSDLs into a new WSDL, performing compression, transcoding, cutting and rendering on service contents by calling the other modules of the set-top box or chip resources, generating optimized service contents, and outputting the optimized service contents to different terminals.