The invention relates to a built-in GIS used partial discharge ultrahigh frequency and light pulse joint detection system and method. The system comprises a monitored object GIS, an ultrahigh frequency and light pulse integrated sensor, a single mode optical fiber, a coaxial cable, a filter and amplifier device, a photoelectric conversion and amplifier device, a two-channel data acquisition and storage device, a control and display device and a printing device. The built-in installation and arrangement of the ultrahigh frequency and light pulse integrated sensor are performed on the monitoredobject GIS shell. The filter and amplifier device and the photoelectric conversion and amplifier device are connected with the two-channel data acquisition and storage device. The two-channel data acquisition and storage device, the control and display device and the printing device are connected in turn. Compared with the systems and the methods in the prior art, the system and the method have the advantages of being simple and practical and reducing the electromagnetic and external visible light interference problem.