A folding lens system includes: a polarization-dependence device, a first optical device, a first polarization controller, a second optical device and a second polarization controller. The polarization-dependence device has a first surface and a second surface opposite to the first surface. The first optical device is located at a side facing toward the first surface of the polarization-dependence device. The first polarization controller is located between the polarization-dependence device and the first optical device. The first polarization controller has the same curvature as the first surface of the polarization-dependence device. The second optical device is located at a side facing toward the second surface of the polarization-dependence device. The second polarization controller is located between the polarization-dependence device and the second optical device. The second polarization controller has the same curvature as the second surface of the polarization-dependence device.