By analyzing the structure of boundary layer, the boundary layer outside the plane bulkhead is viewed as negative lens. The focusing effect of light beam transmission in the airborne laser communication is simulated under the high-speed maneuvering and upper atmosphere conditions. The result shows that there is a direct proportion function between the flight Mach number and the focusing effect under a constant flight altitude. At sea level, for Mach number 2 or more high-speed maneuvering platform, the -FIRs is lowered to less than 8. At the altitudes of 10km and 15km, the ratios can respectively reach to16 and 25. When the ratio comes up to more than 6.3, the BER can be satisfied.