An on-line monitoring system for cable arresters is mainly composed of two parts: data acquisition systems and a data receiving system. The data acquisition systems, which are embedded microcomputer systems, automatically acquire arrester leakage current and counter action signals output by an arrester monitor, process and store data, and transmit the acquired data to the backend-monitoring data receiving system through a GPRS network. The data receiving system uses a server as a hardware platform. The server is arranged in a substation, a power plant or a system operation monitoring center, and forms a monitoring terminal. A client terminal can be easily connected with the monitoring terminal through a PC. The data receiving system is mainly responsible for receiving arrester monitoring data sent by all the data acquisition systems and completing tasks such as comprehensive calculation, display and storage, trend analysis, database management and alarm management. The on-line monitoring system for cable arresters has the characteristics of reasonable composition, convenient and reliable use, and the like.