Abstract: Timely reclosing DC circuit breaker (DCB) can reduce the adverse effect of instantaneous faults and improve the transmission efficiency of DC lines. However, reclosing mechanical DCB may lead to a fault current impulse or line voltage oscillation. To solve this problem, the equivalent circuit of the system during reclosing the mechanical DCB is established, and the transient characteristics of the capacitor voltage during the permanent fault and the instantaneous fault are analyzed. Thereafter, the low-pass filter value of the capacitor voltage increment is used to identify the fault properties, and thus an adaptive reclosing strategy suitable for the mechanical DCB is proposed. Finally, the effectiveness of the proposed strategy is validated using PSCAD /EMTDC simulations. The analysis and simulation results show that the proposed strategy can effectively suppress the fault current impulse during the permanent fault and the line voltage oscillation during the transient fault.