Abstract <p>This article considers current issues of optimization of design and manufacturing technology of cable joints for 6- to 500-kV polymer-insulated cable lines. Special design and process design solutions aimed at increasing the reliability of cable joints are considered, including the introduction of an additional insulation layer and the use of stress cones and electrically strong gels and liquids, as well as internal screens and semiconducting plates. For voltages up to 35 kV, it is recommended to use heat-shrink sleeves, semiconducting plates, and specialized insulating compounds; for lines of 35 kV and above, stress cones, built-in screens, and special coatings are mainly used. The importance of choosing optimal insulating materials and improving the methods for calculating electrical strength to ensure the reliability of high- and extra-high-voltage cable joints is noted.</p>