分析北京地铁房山线闭路电视系统的物理结构、工作原理和构建方法：该闭路电视系统与地铁综合监控系统互联，成为综合监控系统的一个子系统，并与其他子系统进行信息交互和资源共享。从网络结构、数据流、联动等方面，着重阐述闭路电视系统和综合监控系统之间的接口关系。

This paper introduces the structure，working principles and setting up of CCTV in Beijing subway． CCTV interconnects with ISCS and becomes a subsystem of ISCS by which CCTV can exchange information with other subsystems． Interface relationship between CCTV and ISCS is emphatically introduced in terms of network structure，data stream and linkage．