Abstract: The airborne laser sounding system will become an advanced equipment in surveying water depths and detecting underwater targets and possible hazards in the water in 21 century.It is being made cooperatively by Chinese research units to survey Chinese sea-water territories. When making the airborne laser sounding system it is necessary to distribute carefully the accuracy specifications for its subsystems.According to our research the accuracy surveying sea-water depths relates not only to the self-system errors, but also to error sources from the airborne auxiliary equipment.This paper focuses on two error sources influencing on a sounding accuracy:1)auxiliary errors resulting from the airborne accelerometer and sweep equipment; 2)errors surveying sea-water depths by means of the airborne Laser sounding system. Especially, it is pointed out that multicolor laser can be used to determine effectively the refractive corrections in the sea-water, so as to mitigate an influence of the refraction index error on the sounding accuracy.