Abstract: The airborne laser scanning altimetry data contains the 3D coordinates of the laser footprints and intensity of the return pulse. The amount of light that is returned from a target's surface is characterized by the reflection coefficient. For a diffusely reflecting target, the maximum value of reflection coefficient is 100%. For mirror-like or retro-reflecting targets, the theoretical value of reflectivity can exceed 100% by far. The reflection coefficient is, of course, also depending on the wavelength. For the specified airborne laser scanning altimetry, the intense of the reflectivity varies with the interacted material of the object surface. For materials with skinny or glossy surface, the reflectivity figure represents the maximum light return, with the sensor beam exactly perpendicular to the material surface. Airborne laser scanning altimetry data classification algorithm combined with the intensity of laser is studied in detail. The fusion of height data and intensity data can achieve good classification