The invention discloses a 10kV ring main unit AC withstand voltage insulating and isolating apparatuss which includes an insulating cover and an expansion connector. The insulating cover is a telescopic insulating cover and includes an insulating cover 1 and an insulating cover 2. The insulating cover 1 and the insulating cover 2 are L-shaped insulating sheet materials. The insulating cover 1 is higher than the insulating cover 2. The insulating cover 1 and the insulating cover 2 are stacked together through a sliding rail and are intended for covering a circuit breaker inside a cabinet 2. One end of the expansion connector is connected to a plug bushing which is inside a cabinet 1, and the other end of the expansion connector is connected to a ground clamp for performing grounding. According to the invention, the apparatus is advantaged by convenience and flexibility, small size, light weight, reasonable structure, endurability, simple wiring, high efficiency and on-site test safety. The apparatus has excellent effects, for example when applied to 10kV switch cabinet AC withstand voltage tests at the 66kV Nanzhangdang transformer substation, the apparatus can ensure test quality, provides protection in cabinet switching withstand voltage tests, greatly increases the safety and production efficiency of on-site tests, and is safe and reliable.