The utility model discloses a high voltage isolator on -line monitoring system based on modal analysis method, including acquisition unit, laser energy supply unit, device end processing unit and master -control room, acquisition unit involving vibrations and temperature acquisition unit, motor electric current acquisition unit, pivot angle acquisition unit and view acquisition unit, the master -control room includes server end processing unit, WEB server end and backstage display element. This high voltage isolator on -line monitoring system based on modal analysis method passes through vibrational acceleration sensor, temperature sensor, current transformer, angle sensor and gathers high voltage isolator vibration signal, contact temperature signal, drive mechanism motor current signal and pivot angle signal respectively, but view acquisition unit passes through the supplementary monitoring real -time image monitoring of camera, wholly can be in real time to the temperature, the angle, the electric current size, the image is monitored.