A computer device includes a holding structure, a motherboard module and a cover plate. The holding structure includes a holder and a frame. The holder includes a supporting face and an end edge. The frame is connected to the supporting face and arranged adjacent to the end edge. The frame includes an opening and a top bar. The motherboard module, including I/O ports disposed in the opening, is installed on the supporting face. The cover plate covers the opening, a bottom portion of the cover plate is detachably connected to the end edge with a positioning structure, a top portion of the cover plate is detachably connected to the top bar with a fastening structure, the cover plate includes through slots, and the I/O ports are inserted through or disposed corresponding to the through slots respectively, so that the computer device facilitates easy and flexible assembly.