Abstract: An adjustment method of laser light path includes the steps of: having a laser light path to penetrate through a measuring device to obtain at least two laser focal positions of the laser light path, the at least two laser focal positions forming an arc path; applying a focal position-calculating device to calculate coordinate values of the at least two laser focal positions; based on the arc path and the coordinate values of the at least two laser focal positions to apply the focal position-calculating device to calculate a target laser focal position; and, based on the target laser focal position to apply a light modulator to adjust each of the at least two laser focal positions to the target laser focal position. In addition, an adjustment device of laser light path is also provided.