Replacing traditional SF₆ circuit breakers with environmentally friendly 252 kV single-break vacuum circuit breakers in transmission-level power systems is an effective method to reduce SF₆ greenhouse gas emissions. The investigation of breaking velocity characteristics based on vacuum arc mode is important for the successful interruption of vacuum arc. This paper experimentally investigates the vacuum arc mode in the 252 kV single-break vacuum interrupter under different arc currents and breaking velocities using an adjustable breaking velocity operating mechanism. The arcing process at different breaking velocities is classified, and the effect of arc current and breaking velocity on the vacuum arc mode is obtained. Based on this research, a design scheme for breaking velocity characteristics is proposed, effectively reducing the duration of short-gap intense arc mode, thus facilitating the successful interruption of short-circuit currents, which can optimize 252 kV single-break vacuum interrupters.