Abstract: To suppress parameter fluctuations in system commutation and improve commutation success rate, this study takes a certain DC transmission system as an example to analyze its commutation failure mechanism and propose optimization control techniques. The article first establishes a voltage coupling function between converters to quantitatively describe the interactive effects of multi input systems; Then, the zero crossing offset of the commutation voltage is introduced to dynamically correct the turn off area, enhancing the robustness of commutation under asymmetric faults; Finally, an additional intelligent hysteresis trigger adjustment mechanism is designed to synergistically regulate the operating points of the rectifier and inverter sides during faults, suppressing the surge of DC current. The experimental results show that the proposed optimization control technology can alleviate the voltage and current fluctuations in the commutation phase, reduce the number of continuous commutation failures, and improve the reliability of the system commutation after application.