The relation among maximal energy E_max of laser beam, divergence of laser beam and altitude of aircraft is quantified by using USA ANSI standard when aerosol is measured by airborne environment lidar. Maximal laser pulse energy to eye safety at different height is computed when 1064 nm laser pulse energy equals to 532 nm laser pulse energy. The relation among S_L (laser pulse eye safety coefficient), laser pulse energy (1064 nm, 532 nm) and height is educed, which can provide laser pulse eye safety maximal energy setting for the first airborne atmospheric detection lidar in China.