Insulation fault is one of the main faults of insulated tube bus-bar, which seriously threatens the safe operation of the power grid. Therefore, it is of practical engineering significance to study the insulation monitoring method of insulated tube bus-bar. In order to realize the omnidirectional monitoring of the insulation state of the Insulated Tubular Bus-bar, it is proposed to monitor the insulation of the main insulator of the Insulated Tubular Bus-bar with the dielectric loss parameter and the insulation of the outer protective layer of the Insulated Tubular Bus-bar with the ground current parameter. The incremental method is used to measure dielectric loss, and a section of the calibration tube is used to replace the original PT as a reference, which effectively reduces the measurement error introduced by line frequency fluctuation. On this basis, a monitoring system for the insulation state of the Insulated Tubular Bus-bar is developed to measure the dielectric loss and ground current of the Insulated Tubular Bus-bar with high precision. The monitoring system has been put into operation in a 220 kV substation 10 kV Insulated Tubular Bus-bar, and the running results show that the measuring system is effective and practical.