The invention belongs to the field of the power equipment monitoring, and particularly relates to the monitoring on an insulation state of power equipment. According to the invention, a main industrial personal computer, a voltage acquisition unit, a current acquisition unit and a GPS (Global Positioning System) clock server are used as major parts; and by an IEEE1588 time setting protocol, a dielectric loss device has a time setting function. According to the device, the accuracy and the reliability of the dielectric loss measurement are improved and the intelligent transformation cost of electrical equipment is reduced; and the device is effectively applied in the substation intelligent renovation project in Siping City in Jilin Province in the northeast.