The invention discloses a transformer bushing dielectric loss live detection method and system based on transient voltage disturbance. The method comprises the steps of collecting and obtaining electromagnetic transient voltage signals generated by a system connected with a to-be-tested transformer; processing the collected electromagnetic transient voltage signals and obtaining effective electromagnetic transient voltage signal data in a preset frequency range; collecting and obtaining a transformer bushing leakage current when transient voltage disturbance occurs; and computing bushing insulation dissipation factors under different frequencies through utilization of the obtained effective electromagnetic transient voltage signal data and leakage current, thereby finishing bushing dielectric loss live detection of the to-be-tested transformer. According to the method and the system, the transient voltage signals at a position of a guide rod of a transformer bushing inlet is collectedand the transient voltage signals are taken as excitation sources of a transformer bushing insulation dielectric response test, so the live detection of an insulation state of a bushing can be realized, and manpower and time cost when conventional uncharged detection of the insulation state is carried out can be reduced.