The invention discloses a fixture for a key cutting machine, comprising a base, a clamping mechanism and a rotating assembly, wherein the clamping mechanism comprises a first clamping block, a second clamping block, a central shaft and an adjusting piece, wherein one end of the central shaft is connected to the base and sequentially passes through the first clamping block and the second clamping block, wherein the adjusting piece is disposed at the other end of the central shaft for adjusting the distance between the first clamping block and the second clamping block in order to hold the key, wherein the rotating assembly is disposed between the first clamping block and the base, the first clamping block is rotationally connected to the base. Providing that the volume and the size of the key cutting machine fixture do not change, one can freely switch between different clamping surfaces using only a small directional force, which makes for flexible operation, no dead spots and strong applicability.