A GIS ultrahigh frequency sensor fixing device comprises a connecting frame with an inverted-U-shaped main body, a connecting rod, a connecting plate, an insulating supporting rod connecting wheel andan intermediate block. The bottom of the connecting frame is fixedly connected with the lower end of the connecting rod. The connecting plate is fixedly connected with the upper end of the connectingrod. The lower end of the intermediate block is fixedly connected with the connecting plate, and the insulating supporting rod connecting wheel is arranged at the upper end of the intermediate block.The axis of the insulating supporting rod connecting wheel is parallel to the plate surface of the connecting plate, and the distances from the axis to the axes of the left and right connecting rodsare equal. A plurality of connecting grooves used for being connected with a connecting disc fixedly connected with the insulating supporting rod through a middle connecting rod are formed in the rearsurface of the insulating supporting rod connecting wheel, a U-shaped through groove is formed in the insulating supporting rod connecting wheel, and the U-shaped through groove is matched with the middle connecting rod. The lower ends of the two side edges of the connecting frame are each provided with two through holes. The device has the advantages that the operation safety of corresponding measurement workers can be effectively protected, and the falling of the GIS ultrahigh frequency sensor and the damage caused by the falling can be effectively prevented.