When a circuit breaker cuts off a transformer’s different fault types, there will be different voltage recovery processes. Studying on these transient processes provides bases for the section of breaker and the extraction of fault feature. Based on theoretical analysis and simple calculation, this paper uses PSCAD/EMTDC software to model and emulates every fault system. The results show that when a transformer takes place two-phase grounding fault, the peak of recovery voltage between circuit breaker’s both ends is highest. A conclusion is drawn that when to choose a breaker, pay attention to the two-phase grounding fault.