An optical system is provided. The optical system includes a first optical module and a second optical module. The first optical module includes a movable portion, a fixed portion and a driving assembly. The movable portion is connected to a first optical member, and is movable relative to the fixed portion. The driving assembly is configured to drive the movable portion to move relative to the fixed portion. The second optical module is connected to a second optical member, wherein an optical axis passes through the first optical member and the second optical member.