The utility model relates to the technical field of transformer knife switches, in particular to a low-voltage side knife switch of a transformer. The utility model provides a low-voltage side knife switch of a transformer. The low-voltage side knife switch comprises a knife switch body, a fixing rod, an insulator, a fixing plate and a grounding hanging ring, the knife switch body is fixed on thefixing rod, and the insulator is fixedly connected with the fixing rod and the fixing plate. And the grounding hanging ring is arranged on the fixing rod and is used for hanging a grounding wire. According to the utility model, the grounding hanging ring used for hanging the grounding wire is arranged on the fixing rod, so that the grounding wire is convenient, simple and rapid to install and operate, and the problems that a position convenient for installing the grounding wire does not exist, the grounding wire is difficult to install on the transformer and the installation is not firm due tothe fact that the load side of the low-voltage side knife switch is connected with a relatively dense outgoing cable are solved.