A high efficiency micro projection optical engine includes a light source module, a lens assembly, a micro display panel and a projection lens. An image of the luminous surface of light emitting elements of the light source module is formed in the vicinity of the micro display panel. The micro display panel is arranged on the path of emission light of the lens assembly to modulate incident light and obtain image light with image information. The projection lens is used to project the image information on the micro display panel and form an image onto a screen. The optical engine enhances efficiency by means of critical illumination.