By analyzing the effect of some factors to air target, the relation between the factors and laser pulse echo parameter has been studied.Considering the effect of distance, speed, entering angel and target size to the time delay and broadening of pulse, the relation model is built,and the main conclusion of the different effects of different factors to pulse time delay and broadening is obtained. Based on the discussion of the process of laser atmospheric tansmittance in the slant path, a calculating method of laser atmospheric slant transmittance is proposed, and the general model of energy attenuation of laser tansmittance is improved and the exponential decay of laser energy changing with the increase of distance and decreace of projection area is concluded. Based on the experiment system built,the measured echo datas are analyzed. Through calculating and comparing the theoretical result and measured result, the relative error is in 6% and it is a better coincidence, which has verified the effectiveness of built model. The conclusion has significant referenced value on the inverse of air target situation.