Partial discharge detection is crucial to ensure the safe operation of high-power systems. In this paper, a surface plasmon resonance D-type photonic crystal fiber sensor for partial discharge detection in high-voltage equipment is proposed, and the scheme employs a photochromic gel as a sensitive unit for sensing the ultraviolet radiation generated by partial discharges. The refractive index of the gel varies with the radiation intensity, affecting the coupling resonance wavelength between the fiber core and the surface plasmon modes. The performance of the sensor is analyzed theoretically and simulated firstly by the full vector finite element method, then the geometric parameters of the sensor are studied to optimize the sensitivity of the sensor, and experimental verification is carried out finally. The results show that the sensitivity value of the designed sensor can reach up to 2.4 nm/mW·cm^-2. The simple structure and low cost of the sensor provide a reference for the study of fibre optic partial discharge sensing.