Optical path processing device for projecting device and projecting device

The invention provides an optical path processing device for a projecting device and a projecting device, wherein the optical path processing device comprises a first part, a reflecting mirror device and a second part which are arranged in a same optical path; the first part is used for processing and outputting input light beams; the first part is positioned in a first zone on one side of the reflecting mirror device; the reflecting mirror device limits the light beams of the first part to be output to reach a second zone on the other side of the reflecting mirror device and reflects the light beams of the first part to be output to reach the second part positioned in the first zone, so as to be utilized by the second part for imaging, wherein the first part and the second part are oppositely arranged in a manner that: when the optical path section in the first part is positioned in a horizontal plane, the optical path section of the second part is not in the horizontal plane; the area of the plane occupied by an optical engine of the projecting device can be greatly reduced, and metal parts for bearing optical lenses can be staggered, the interior of a product can be kept together in a compact manner, so that the size of the product can be minimized.