The utility model provides a flexible IGBT modular unit for direct current transmission, including the installation frame, the front portion of installation frame has set firmly submodule piece crimping unit, two installation end plates that submodule piece crimping unit includes the orientation is extended about along middle frame and sets firmly both ends about middle frame, and two installation end plates set firmly on the installation frame, and middle frame is last to install about along orientation alternate two at least sub - modules and the intermodule insulating spacer of arranging in proper order, is equipped with on the two installation end plates to be used for the cooperation to use with clamping position on controlling the orientation two clamping device of submodule piece and intermodule insulating spacer, each submodule piece include IGBT and thyristor respectively, the rear portion of installation frame sets firmly the electric capacity with each submodule piece one -to -one electrical connection. Make each submodule lump formation series connection crimping structure, through setting up each the submodule piece of two clamping device clamping position on two installation end plates, reduced installation spare part, effectively simplified submodule piece installation crimping structure.