The present invention discloses an adjustment device and method thereof which are applied for adjusting a photosensitive element. The adjustment device comprises a first platform, a second platform, a third platform and a cover. The first platform comprises a curved surface body and a positioning elastic element. The second platform, having a recess corresponding to each curved surface body and having a loading support portion, is arranged on a side of the first platform. The third platform is arranged on the other side of the first platform, and when the third platform, moves in an axial direction, the first and second platform moves together with the third platform. The cover compresses the photosensitive element against the second platform. When the inclination of photosensitive element is adjusted by the adjustment device, each curve surface body and each recess keep in contact due to the expansion of each positioning elastic element.