The present disclosure provides an optical system, including a first optical mechanism. The first optical mechanism includes a first movable part, a fixed assembly, a first driving assembly and a guiding assembly. The first movable part includes an optical element. The first movable part is movable relative to the fixed assembly. The first driving assembly is configured to drive the first movable part to move relative to the fixed assembly. The guiding assembly is configured to guide the first movable part to move relative to the fixed assembly. A friction force is generated between the first movable part and the guiding assembly, and the first movable part is temporarily positioned on the fixed assembly through the friction force.