A cable connector joint fastening structure includes a male connector, a female connector, and a fastener. The male connector includes a male terminal body with a male terminal joint, a freely rotating screw sleeve locked around the external periphery of the male terminal joint. The female connector includes a female terminal body with a female terminal joint, and an insert space formed in the female terminal joint for inserting the male terminal joint, and the screw sleeve is screwed and coupled to the female terminal joint. The fastener includes a pivot portion formed at an external side of the female connector, and a locking arm pivotally installed onto the pivot portion, extended towards the male terminal body, disposed across the screw sleeve, and locked to the male connector.