The invention relates to the field of high-voltage power supply and distribution, particularly to a high-voltage circuit breaker and a nozzle thereof, so as to solve the problems of inconvenient processing and installation of the nozzle since the existing nozzle is connected with a flange through threads. In order to solve the technical problem, one end of the nozzle used for the high-voltage circuit breaker is processed with notches extending along the axial direction, wherein the notches allow the tail end of the nozzle to form elastic contact fingers which can deform in a stretchable manner along the radial direction, the elastic contact fingers are processed with convex edges, and grooves which can be clamped with the convex edges in a matched manner are processed in a flange. The axial fixation of a workblank is achieved by utilizing the notches in the nozzle when using a tooling for fixing the workblank in a radial manner, the axial movement of the workblank during the processing process is prevented, and the processing precision is guaranteed; and the convex edges on the nozzle can be clamped and matched with the grooves in the flange by inserting the nozzle into the flange through pressing the elastic contact fingers in assembly without using a tool for auxiliary fastening, thereby avoiding the resulting secondary deformation and processing design of the tool and operation tooling.