Attenuation-adjustable partial discharge measurement system and method

The system comprises a pump light source, a wavelength division multiplexer, a DFB-FL, a single-mode fiber, an adjustable attenuator and an FBG which are arranged in sequence, the output end of the wavelength division multiplexer is further connected with a photoelectric detection structure, the public end of the wavelength division multiplexer is connected with the DFB-FL, and the public end of the wavelength division multiplexer is connected with the single-mode fiber. The rear end of the DFB-FL is connected with the single-mode optical fiber with a set length, the tail end of the single-mode optical fiber is wound into an optical fiber ring and is connected with the adjustable attenuator, the FBG serves as an optical fiber reflector and is used for reflecting laser back to a resonant cavity of the DFB-FL for interference, and the adjustable attenuator is used for adjusting the intensity of the reflected laser. According to the invention, the DFB-FL and the single-mode optical fiber are used for sensing at