The invention discloses a heat dissipation device for a power distribution cabinet, which comprises a power distribution cabinet body. The outer side of the power distribution cabinet body is providedwith a heat dissipation mechanism. The heat dissipation mechanism comprises a heat dissipation box body, a heat dissipation assembly and a power assembly. An annular groove is formed in the heat dissipation box body, heat dissipation through holes are evenly formed in the side surface of the heat dissipation box body, the power assembly comprises a driving motor, a connecting transverse plate isfixedly installed at the output end of the driving motor, a connecting vertical plate is fixedly installed at the end of the connecting transverse plate, and the connecting vertical plate is installedin the annular groove in a sliding mode. As the annular groove and the driving motor are arranged, the driving motor rotates, the heat dissipation assembly is driven to rotate above the power distribution cabinet body, so that dynamic heat dissipation of the heat dissipation assembly is realized, poor heat dissipation effect caused by non-uniform heat dissipation due to the fact that the heat dissipation assembly dissipates heat at the same position all the time is avoided, effective heat dissipation of the power distribution cabinet body is realized through dynamic heat dissipation of the heat dissipation assembly, and the service life of the power distribution cabinet body is prolonged.