Due to dynamic interaction between converters, design of control parameters of multi-converters medium-voltage DC (MVDC) power system is much more complicated than of a single-converter situation. Open-loop and closed-loop transfer functions considering control-loops dynamic interaction between converters are developed, which are suitable for studying influence of control parameters on system stability. With the above transfer functions, a system-level control parameter design procedure for dynamic stability (e.g., oscillation frequency and damping factor) of system is proposed. If there are many converters, computational burden of system-level control parameters design procedure will be huge. For this reason, a control parameter sharing method is further proposed in this paper, which is based on dynamic interaction mechanism between converters. In this sharing method, control parameters of equivalent reduced-order model of the system are shared with each converter, so calculation burden of control parameters of system is reduced significantly. Consequently, dynamic stability of the system can be designed by equivalent reduced-order model. Experiments are conduced to validate the system-level control parameter design procedure.