Aiming at the threat of laser active detection technology to electro-optical devices, a method using photosensitive surface inclined design to reduce the laser echo energy was proposed, so as to improve the system performance of anti-laser detection. A middle and long wave dual band infrared anti-laser detection optical system was designed whose photosensitive surface inclined 5°. The aberration of the photosensitive surface was corrected by using the free-form surface. The designed system operating band was 3-5 μm, 8-12 μm. The field angle was ±2.4°, the number of F was 2. This result shows that the transmission function of the two bands is higher than 0.38 at the frequency of 17 lp/mm of Nyquist, which satisfies the requirement of imaging quality of infrared system. Then, through the anti-chase track analysis, the detection distance of the system is effectively reduced.