Optical imaging system

This invention discloses an optical imaging system, which includes an imaging unit, at least one first light guiding unit, and at least one second light guiding unit, for imaging an image for an object in a space. The imaging unit defines a first side and a second side. A first optical path is defined from the object to the first side, and a second optical path is defined from the second side to the image. The first light guiding units are disposed at the first optical path for guiding a light from the object passing through in the first optical path. The second light guiding units are disposed at the second optical path for guiding the light further passing through in the second optical path, such that the image is imaged in the space to reduce the size of the optical imaging system.