With the rapid development of the IPTV industry worldwide in recent years,IPTV services typically represent triple-play services. However,a lack of standards for the interfaces between the terminal and the platform has become the bottleneck in IPTV development. In order to fulfill IPTV standardization,it is necessary to conduct studies on the relationship between the IPTV system and the three networks (the broadcast network,communications network and Internet). The horizontal interface model between the IPTV terminal and the three networks is a solution to architecture of the standard interface model at the current phase of service integration. A vertical protocol interface model based on the horizontal interface architecture is proposed to validate the development trend of IPTV protocol interface standardization towards the all-IP system. Based on the standard protocol interfaces,introduction of middleware effectively lowers the threshold of IPTV application development. However, a lack of standards for the interfaces between the terminal and the platform has become the bottleneck in IPTV development. In order to fulfill IPTV standardization, it is necessary to conduct studies on the relationship between the IPTV system and the three networks (the broadcast network, communications network and Internet). The horizontal interface model between the IPTV terminal and the three networks is a solution to architecture of the standard interface model at the current phase of service integration. A vertical protocol interface model based on the horizontal interface architecture is proposed to validate the development trend of IPTV protocol interface standardization towards the all-IP system. Based on the standard protocol interfaces, introduction of middleware effectively lowers the threshold of IPTV application development.