An optical system is provided. The optical system includes a second optical module for driving a second optical element. The second optical module includes a second immovable part, a second movable part, a second driving assembly, and a second guiding assembly. The second movable part is used for connected to the second optical element. The second movable part is movable relative to the second immovable part. The second driving assembly is used for driving the second movable part to move relative to the second immovable part. The second guiding assembly is used for guiding the second movable part to move relative to the second immovable part in a first dimension.