The terrorist criminal activities, especially the explosive incidents, have a large scope of harm and adverse effects. The safety detection of public places, such as subway stations, train stations, airports, docks, and other places with high traffic and complex backgrounds, urgently requires real-time and rapid detection of the hidden explosives. The explosive detection equipment can effectively ensure people’s travel safety. A laser detection device for explosives is designed to address the shortcomings of existing explosive detection equipment and methods, utilizing the infrared laser temperature rise effect of the explosives (such as TNT and RDX). Using a high collimation optical system to irradiate the detected target from a long distance, an infrared thermal imager and a visible light camera are used to simultaneously receive the image of the detected target. Temperature difference features are extracted through infrared image recognition technology, and combined with visible light camera review and judgment. A laser detection device for explosives is obtained with a non-contact, fast, and safe characteristics. This article mainly focuses on the optical design of a high collimation laser irradiation optical system. The working distance is greater than 2000 mm, the beam divergence angle is less than 25 μrad, and a 100 W power adjustable CO2 laser is used. The laser output beam waist is 1.8 mm, and the diameter of the irradiated area of the detected target is greater than 160 mm. The development and application of this explosive laser detection equipment will provide a practical technical means for the security inspection of explosives in key areas of public transportation in China.