An external display module is provided, which is adapted to be detachably connected to an electronic device. The external display module includes a module base and a first screen unit. The module base includes a first base side, two first tracks and at least one first slot. The first screen unit is rotatably connected to the module base, wherein the first screen unit includes a first screen, a first shaft, at least one first guiding member and two first blocks, the first shaft is disposed on the edge of the first screen unit, the first guiding member is affixed to the first shaft and is rotated with the first shaft, the first block is connected to the first shaft, the first guiding member is inserted into the first slot and is guided by the first slot, and the first block is adapted to slide in the first track.