The invention provides a cable operating temperature measuring device installed on a cable hoop. The cable operating temperature measuring device comprises a cable hoop, a tapered temperature measuring unit and a temperature collecting unit. The cable hoop sleeves the outer side wall of a cable. The tapered temperature measuring unit that is arranged at the cable hoop and is in contact with the outer sidewall of the cable is used for measuring temperature data of the outer sidewall of the cable. The temperature collecting unit that is arranged at the cable hoop and is connected with the tapered temperature measuring unit is used for receiving the temperature data. The cable operating temperature measuring device has the following beneficial effects: since the tapered temperature measuringunit and the temperature collecting unit are arranged at the cable hoop, the temperature measurement and display of the outer sheath layer of the cable during the operation process of the cable are carried out and thus the temperature of the cable structural layer is analyzed, so that the temperature at the temperature bottleneck point in the cable line is effectively monitored. Meanwhile, the device having a simple structure and stable performances is convenient to install.