Disclosed are an optical system and a virtual reality device. The optical system comprises a display unit (10) and a first lens (20), the first lens (20) comprises a first surface (21) and a second surface (22), and the second surface (22) has a planar structure; an optical splitter is provided between the first surface (21) and the display unit (10); a first phase retarder (30) and a polarization reflector (40) are provided at a side of the first lens (20) away from the display unit (10), and the first phase retarder (30) is provided between the first lens (20) and the polarization reflector (40); and light emitted from the display unit (10) enters into the first lens (20) from the first surface (21), and is sequentially reflected by the second surface (22) and the first surface (21), and then exits the optical system from the second surface (22).