Abstract: High-voltage circuit breakers use the mechanism of AC arc zero-crossing extinguishing to complete current breaking, however, with the construction of UHV project and DC power grid, the phenomenon of current zero delay will appear in power systems, which will affect the interruption of high-voltage circuit breakers. In this paper, the cause of current zero delay is analyzed by using the fault circuit of asynchronous three-phase short-circuit, and the circuit is simulated by the PSCAD software. The calculation results show that when B and C two-phase short-circuit occurs, and the initial phase angle of A-phase current source voltage is 90° or 270°, the circuit has the largest DC component; when two-phase short-circuit develops into three-phase short-circuit after 5 ms, positive current zero delay phenomenon occurs in phase B, and negative current zero delay phenomenon occurs in phase C when two-phase short-circuit develops into three-phase short-circuit after 15 ms. Based on this phenomenon, a synthetic test circuit of current zero delay is developed, and the current zero delay interruption test of high-voltage circuit breaker is realized. The results show that the arc resistance produced by the circuit breaker during the interruption process will reduce the DC component in the circuit, resulting in the decrease of the current zero delay time.