In order to simulate the spectral distribution difference between the target and the interference in real scene, a zoom optical engine with two channels and the same caliber has been designed based on dual digital micro-mirror device (DMD), it includes projection optical system and two illumination optical systems. The optical engine directly illuminates two DMD target surfaces respectively with long-wave infrared (LWIR) and mid-wave infrared (MWIR) Kohler telecentric beam. It uses spatial stereoscopic layout to get avoid of interference between different optical paths. The design result shows that the illuminance uniformity of illumination optical system is better than 94%. The modulation transfer function (MTF) values of zoom projection optical system are better than 0.4 and better than 0.7 at 10 1p/mm respectively in bands of LWIR (8~12 μm) and MWIR (3.7~ 4.8 μm). And the distortion is better than 0.5%, which meet the requirements.