The utility model belongs to the technical field of auxiliary mounting equipment in engineering construction, and particularly relates to an adjustable supporting frame for mounting a GIS equipment busbar barrel. The adjustable supporting frame comprises a supporting base, a supporting rod and a sliding bar part, wherein the supporting rod is arranged on the supporting base; the sliding bar part is arranged on the supporting rod; the sliding bar part is in sliding fit or threaded fit with the supporting rod; the sliding bar part can perform a lifting movement relative to the supporting rod in the direction of the plumb line; a supporting surface used for supporting the busbar barrel is arranged at the top end of the sliding bar part; the adjustable supporting frame for mounting the GIS equipment busbar barrel is further provided with a positioning part. According to the utility model, the adjustable supporting frame is simple in implementation model and easy to operate; the supporting rod and the sliding bar part can even adopt high-strength steel structure material to ensure that the supporting rod and the sliding bar part can bear weight of a butt-joint unit and the actual service life can be further ensured; once the but-joint of the busbar barrel is completed, the whole supporting frame can be moved and reutilized in a new supporting point, so that the reutilization rate is extremely high.