Abstract: Quench protection system plays an important role in superconducting magnet power supply system, as it can transfer and consume magnet energy rapidly. In the project of Comprehensive Research Facility for Fusion Technology (CRAFT), the technical requirement of breaking 100 kA direct current (DC) is proposed for the quench protection system, in which the vacuum circuit breaker is used as the switch of transfer branch. In this paper, a 100 kA DC vacuum circuit breaker with series structure is designed for the CRAFT project’s quench protection system, and the prototype is manufactured. In field test, with the cooperation of artificial zero-point circuit, the vacuum circuit has completed the 100 kA (DC) breaking test successfully.