Embodiments of the invention disclose an overvoltage protection circuit and method of a direct current circuit breaker. The input end of the overvoltage protection circuit is connected with a currentconversion circuit while the output end of the overvoltage protection circuit is connected with a smoothing reactor; the overvoltage protection circuit comprises a first lightning arrestor, a direct current circuit breaker and a controllable lightning arrestor; and the valve side end of the direct current circuit breaker is connected with the first lightning arrestor while the circuit side end ofthe direct current circuit breaker is connected with the controllable lightning arrestor. Embodiments of the invention also disclose an overvoltage protection method of the direct current circuit breaker.