The invention discloses a capacitive high-voltage cable joint partial discharge built-in sensor structure which includes a sensor and a high-voltage cable. The cylindrical sensor includes a dielectric film, a copper foil electrode, a buffer layer and a metal shell in sequence from inside to outside. The copper foil electrode and the dielectric film are tightly bonded to form a sensor electrode. The sensor is provided with a radio-frequency cable joint. The high-voltage cable includes a conductive wire core, an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a semi-conductive water blocking tape, a corrugated aluminum sheath, an anti-corrosion layer and an outer sheath in sequence from inside to outside. The periphery of the inner semi-conductive layer is connected with the dielectric film. One end of the sensor is connected with a connector with a spiral structure inside. The internal spiral structure of the connector matches the corrugated aluminum sheath of the high-voltage cable. The periphery of the corrugated aluminum sheath is connected with the internal spiral structure. The sensitivity of high-voltage cable partial discharge monitoring is improved. The capacitive high-voltage cable joint partial discharge built-in sensor structure is durable, and very convenient to install and disassemble.