Abstract: In order to coordinate with the ground detection tracking system for detecting the flight target, we designed an air-based monochromatic beacon system. A 40W high-power semiconductor laser is used as the light source of the system, which has a certain beam divergence. As the beacon system should meet the requirements of smaller in size, lighter in weight and faster in heat dissipating to fit the air-platform, we designed the aluminum shell as fin chip in onepiece for laser, which helped solve the heat dissipation problem and reduce the system weight. To achieve the 60A high constant current, we need to drive the 40W semiconductor laser module in the limited room, the principle of diphase overlay synchronous and buck transformation circuit structure is adopted. To make the laser output power and central wavelength stable in high altitude, we designed the temperature control system with digital and analog hybrid for heating or cooling. The ZEMAX is used to design the structure of the beam expander device with double-concave lens group, which can regulate the angle of divergence of the light beam. By conducting the environmental assessment and test, we proved that in the 0℃～15 ℃ environment, the stability of the output power and the control precision of the central wavelength could meet the requirements.