Expansion tool and expansion tool kit

The expansion tool is suitable for expanding an axial through hole of a middle insulation joint of a cable and comprises two sets of expansion assemblies which are respectively arranged at two ends of the middle insulation joint and respectively comprise an expansion module which is provided with an expansion part suitable for expanding the axial through hole; the clamping assembly is used for clamping and fixing the expansion module during expansion of the axial through hole; the guide assembly comprises a guide module, and the guide module is suitable for being partially inserted into the axial through hole so as to guide the expansion part to enter the axial through hole; the tensioning mechanism is suitable for tensioning the two sets of expansion assemblies in a mode that the two sets of expansion assemblies located at the two ends of the middle insulation joint are made to get close to each other, so that the expansion parts enter the axial through hole under the guide of the guide module to enlarge the