With the rapid development of the urban distribution network, the requirements for power supply reliability are also getting higher and higher. The importance of the ring network cabinet as the distribution network connection and the power transmission equipment is self-evident. However, due to environmental influences, construction processes and other factors, there is often a partial discharge phenomenon in the ring network cabinet, which affects the stable operation of the equipment and endangers the safety of the power system. The general classification of partial discharges in ring network cabinets can be divided into four categories: suspension discharge, creeping discharge, corona discharge and multi-point discharge. The corresponding characteristics of different partial discharge types and the damage to the ring network cabinet are different. From the trinity of the amplitude diagram of the ultrasonic detection method, the phase diagram of the ultrasonic detection method, and the waveform chart of the ultrasonic detection method, the characteristics and differences of different partial discharge types are compared. Compared with the traditional ultrasonic method, this method detects more parameters , Can achieve accurate detection. Based on this, the ultrasonic method is used to identify the partial discharge type of the ring network cabinet, which not only can deepen the understanding of partial discharge, but also has practical practical significance, and can lay a solid theoretical foundation for further partial discharge positioning.#$NLKeywords: Ultrasonic method; partial discharge; ring network cabinet; discharge type.