Abstract: Direct current circuit breakers (DCCBs) are extensively utilized in flexible DC transmission systems, with their cost being intricately related to the breaking current. An adaptive current-limiting control structure tailored for half-bridge modular multilevel converters (MMCs) has been developed with the aim of reducing the breaking current of circuit breakers. By examining the short-circuit current characteristics on DC side of MMC, the variation in the input impedance amplitude of the converter station is utilized to indicate the extent of the fault. The coefficient K_f, which defines the fault depth of the converter station, is determined. K_f is incorporated into the control structure of MMC to align it with the reference value of the bridge arm voltage. A proposed method for adaptive current limiting control addresses DC side short circuit fault of MMCs. The model of the half-bridge MMC flexible DC transmission system is created using power systems computer-aided design/electromagnetic transients including DC (PSCAD/EMTDC) platform to model the clearance of DC side short-circuit faults and validate the effectiveness of current limiting control. The simulation results demonstrate that the proposed adaptive current limiting control technique can effectively implement differentiated current limiting control depending on the diverse fault depths of MMC. The breaking current of DCCB is reduced and the fault clearing speed is improved by this approach.