The invention relates to a novel fluorescent optical fiber temperature testing system of a switch cabinet, which comprises a tester and a temperature measuring system, wherein the tester mainly comprises a housing, a power switch, a display screen, an alarm lamp, a sensor interface module, optical fiber sensor interfaces, an optical fiber, a fluorescent probe, a communication interface and a controller; the temperature measuring system comprises fluorescent optical fiber sensors, shunt boxes and a PC (Personal Computer); the fluorescent optical fiber sensors mainly comprise fluorescent probes and optical fibers; the sensor interface module is arranged on the housing; the optical fiber sensor interfaces are arranged on the sensor interface module; the power switch, the display screen, the alarm lamp and the communication interface are arranged on the surface of the housing; the controller is arranged in the housing; the fluorescent optical fiber sensors are connected onto the tester via the shunt boxes; and the tester is connected with the PC via the communication interface. The system achieves on-line detection, can isolate high voltage in the switch cabinet and has the advantages of stability, reliability, real time, on line, no maintenance, automatic operation and the like.