An adjustable stroke length percussion massage device includes a stroke arm connected to a piston which is connected to a massage tool for providing a massage to a user. The stroke arm is secured to a crank pin of a crank mechanism which includes a rotatably connected crank housing and crank base, the crank pin being movably secured between the crank housing and crank base such that the crank pin moves from a first end to a second end of a sliding groove located in the cam housing when a rotation direction of the single unit is reversed by a motor. When the crank pin is moved from the first end to the second end of the sliding groove, a stroke length of the piston is changed.