This present invention discloses an optical mouse and a parameter calibration method thereof. The optical mouse includes: a light source, an image capturing unit, a memory unit and a processing unit, and the parameter calibration method of the optical mouse includes: capturing images formed by the reflective light projected from the mouse pad when the optical mouse is placed upon the mouse pad and has a relative displacement between the mouse pad, and then producing image frames according to the images; determining if any pattern information is found in the image frames; further, setting parameters of the optical mouse when at least one of the pattern information is found in the frames, in which, the pattern information is composed of a pattern of the mouse pad.