The utility model discloses a system for the on-line monitoring of the insulating dielectric loss angle trend for high-voltage cables under the condition of intersected interconnection, and the system comprises a signal collection part, a signal transmission part, and a signal processing part. The signal collection part comprises a power-frequency current sensor, a voltage transformer, a signal transmission cable, a data collection card, and a pre-posed industrial control computer. The signal transmission part comprises a local area network line and an optical fiber network system. The signal processing part comprises an upper computer and a centralized control center server. The power-frequency current sensor and the voltage transformer are respectively connected with the pre-posed industrial control computer through signal transmission cables. The upper computer is connected with the pre-posed industrial control computer through the local area network line. The centralized control center server is connected with the upper computer through the optical fiber network system. The system can monitor the insulation condition of three-phase intersected interconnected high-voltage cables successfully, achieves the monitoring and analysis of the variation trend of the dielectric loss angles of the cables, transmits the safe status information of the cables to the server for display in a real-time manner, and achieves the early-warning and prompt for monitoring abnormity.