An optical projection device including an illumination system, a reflective light valve and a projection lens is provided. The adjustable reflection sheet is disposed behind the adjustable rod integrator along the light transmission path of the light beam. In addition, the reflective light valve is disposed behind the adjustable reflection sheet along the light transmission path of the light beam. The adjustable rod integrator can shift the light transmission path of the light beam so as to be incident to the reflective light valve. Moreover, the projection lens is disposed behind the reflective light valve along the light transmission path of the light beam. The adjustable reflection sheet can shift the light transmission path of the light beam so as to pass through the stopper of the projection lens.