The invention discloses a computer all-in-one machine. The all-in-one machine comprises an all-in-one machine body, and a heat dissipation system and an adjustable supporting rack are arranged on theall-in-one machine body; the heat dissipation system comprises a plurality of heat dissipation areas and a plurality of auxiliary heat dissipation mechanisms; the auxiliary heat dissipation mechanismscomprise transmission components, fans and heat dissipation holes, and a sealing plate which is composed of two semi-circle plates is arranged in each heat dissipation hole in a sliding mode; the adjustable supporting rack comprises a supporting rod and a supporting base adjustment mechanism which are connected through a rotation mechanism, the supporting base adjustment mechanism comprises a hollow supporting base, and a clamping disk is rotatably connected into the supporting base; a plurality of movable clamping claws which are matched with the clamping disk are evenly distributed on the clamping disk, a guide cylinder which is located in the supporting base is arranged on each movable clamping claw, and a limit component is arranged between each movable clamping claw and the corresponding guide cylinder; one end of each movable clamping claw penetrates through the supporting base, and a supporting pad is connected to the end, located outside the supporting base, of each movable clamping claw. Compared with the prior art, the computer all-in-one machine has the advantages that the heat dissipation effect is improved, and the base has good stability and unique appearance.