The transition joint connects between existing oil-filled cables and extruded dielectric cables. They comprise the stop joint with oil-impregnated paper insulation and epoxy bell mouth at side of oil-filled cables. They also comprise prefabricated type joint with stress relief cone based EPR(Ethylene-Propylene Rubber) and mechanical devices at side of extruded dielectric cables. They are designed to fit with controlled interference over the cable insulation and is able to follow the cable's diameter variations still guaranteeing under any service condition a sufficient positive pressure to control the electric field concentration. Each components fully examined and tested in the factory. They are currently available at the voltage range up to 300kV and the maximum allowable cable conductor size is 3000mm-(6000kcmil).