Satellite Laser Altimeter multiple mode waveforms are composed of sub-pulses generated from several targets. According to the spatial distribution characteristics of multiple mode targets, the geometric modeling of the sub-target was realized by using the parameters such as the slope angle, the area, the center position and the height. Combined with the basic definition of the target response function, the expression of the sub-target response function was built up by using the line integral method. Meanwhile, the mathematical models of laser ranging and its corrected value for sub-target were derived on the basis of the first order moment theory. Using some parameters of Geoscience Laser Altimeter System(GLAS) as input, the influence of slope angle, area and the center position on the shape of received pulse waveforms and the corrected value of laser ranging was simulated by numerical simulation method. The results show that the corrected value of laser ranging becomes larger with the increase of the slope angle, the area and the center position of sub-target. As for the sub-target with low relief, moderate relief and high relief, the corrected value of laser ranging can be reached at 1.33 m, 4.98 m and 12.07 m, respectively, which exerts a tremendous influence. In term of the regularities distribution of the corrected value of laser ranging, its theoretical expression is described with linear functions by using slope angle, area and the center deviation distance as variables. The conclusion has important guiding effect for the improvement of laser ranging accuracy for multiple mode targets.