Abstract: Aiming at the pre-charging inrush current and control challenges of the arm multiplexing alternate arm converter(AM-AAC) during the initial startup phase, a pre-charging control strategy suitable for AM-AAC is proposed to ensure the reliable commissioning and stable operation of the converter. Firstly, the topological structure and operating principle of AM-AAC are analyzed. Secondly, according to its unique switching combination characteristics, the entire pre-charging process is divided into several operating stages, and the equivalent mathematical models for each stage are respectively constructed. On this basis, the collaborative control logic involving the selector switches, direction switches, and sub-modules, as well as the switching thresholds between charging stages, are designed in detail, and the key parameter design criteria for the current-limiting resistor are derived. The Matlab/Simulink simulation and hardware-in-the-loop experimental results demonstrate that the proposed pre-charging control strategy and current-limiting resistor design criteria can ensure that the sub-module capacitors and DC support capacitors of AM-AAC achieve a smooth and rapid voltage rise without inrush current. The voltage balance among sub-modules is well-maintained, and the capacitors are charged to the rated voltage. Furthermore, the provided design criteria for the current-limiting resistor can effectively balance the pre-charging time and the current-limiting performance to a certain extent.