Mechanical DC circuit breakers have become an irreplaceable part of flexible DC power grids because of their advantages of high economy, low con-duction impedance, and reliable control. However, the large volume of the charging circuit and the high interruption pressure in low current are still the problems it faces. To address the aforementioned issues, a Coupled Self-charging Mechanical DC Circuit Breaker (CSC-DCCB) is proposed. This innovative solution mitigates the risk of switch arc reignition during the commutation process by incorporating a self-charging circuit. The energy consumption process of metal-oxide varistor will cause the capacitor to complete recharging, and this voltage will be used for the reclosing of the CSC-DCCB. Secondly, the parameter of the CSC-DCCB is optimized to achieve a lower overall capacity of the circuit breaker and the rated voltage of the converter switches, which retains the traditional low conduction loss. Finally, the feasibility of CSC-DCCB is validated through PSCAD, the technical parameters of CSC-DCCB are compared with traditional DCCB, showing that CSC-DCCB has better economic efficiency.