A micro light-emitting diode display device and a sub-pixel circuit thereof are provided. The sub-pixel circuit includes a switch unit, a selection driving unit and a light-emitting unit. The switch unit receives a data signal. The selection driving unit is electrically connected to the switch unit, and electrically connected to a first voltage. The light-emitting unit includes two micro light-emitting diodes, which are electrically connected to the selection driving unit. The first ends of the micro light-emitting diodes are connected to the selection driving unit. The second ends of the micro light-emitting diodes are electrically connected to a second voltage. The selection driving unit selects one of the micro light-emitting diodes to emit light according to the data signal transmitted through the switch unit.