Abstract: In order to clarify the evolution law of the related physical parameters during the development of partial discharge of the needle plate electrode inside a transformer, we established the mapping relationship between partial discharge and the development of faults, and improved the operation and maintenance level of the transformer. Moreover, we established a research platform for the development of needle plate electrode partial discharge in oil-paper insulation, and used high-frequency current coils, SiPM, ultrasonic sensors and ultra-high frequency sensors to simultaneously measure the physical parameters at various stages of partial discharge development. The results show that the partial discharge stage of needle plate electrode can be divided into the development stage, stagnation stage, and pre-breakdown stage. In the development stage, statistical parameters such as the discharge volume of pulse current signals and the pulse repetition rate of UHF signals have increased significantly. Except for the amplitude of the pulse current signal, the other characteristic parameters are significantly reduced during the stagnation phase, and then increase again until entering the pre-breakdown phase. The relevant conclusions provide a reference for establishing the "active" pre-protection line of transformers.