A method for adjusting an optical axis of an optical disc drive. The method includes the following steps. A first reflecting member is disposed on a turntable of the optical disc drive, and is rotated along with the turntable. A laser light is emitted on the first reflecting member by a laser collimator, and a normal vector of the turntable is measured based on a light point reflected to the laser collimator from the first reflecting member. A second reflecting member and a third reflecting member are disposed on a guide bar of the optical disc drive. A first initial vector and a second initial vector are measured based on a light point reflected to the laser collimator from the second reflecting member and the third reflecting member. The guide bar is adjusted based on an oblique vector of an optical of an optical pickup of the optical disc drive, the normal vector of the turntable, the first initial vector, and the second initial vector so that the optical axis of the optical pickup is parallel to the normal vector of the turntable.