The invention discloses an online monitoring system and method of a conductor of a cable intermediate joint, and a manufacturing method thereof. The system comprises a cable conductor connecting pipecovering and connecting a cable conductor at the cable intermediate joint; a joint electrode covering the outer side of the cable conductor connecting pipe and made of a first transparent material; ajoint stress cone insulating material layer covering the joint electrode and made of a second transparent material; an outer shielding layer arranged on the joint stress cone insulating material layerand made of a third transparent material; a physical quantity measurement device arranged on the cable conductor connecting pipe for detecting a physical quantity parameter of the conductor of the cable intermediate joint; a light source generation device arranged on the surface of the outer shielding layer for irradiating the physical quantity measurement device; an image obtaining device arranged on the surface of the outer shielding layer for obtaining image information of the physical quantity measurement device; and a signal processing unit for detecting the physical quantity informationof the conductor of the cable intermediate joint according to the image information.