Power-density distribution and the centroid distribution of target laser sparkle in turbulent atmosphere are analyzed,which explains the randomness of power-density distribution. The receiving models of laser rangefinders with two conditions that the area of the target is not smaller or smaller than the area of the sparkle are built respectively. Then,the effect of deviation between sighting axis and receiving axis on detecting probability is discussed. The curve of detecting probability varying with deviation between sighting axis and receiving axis is showed. The results show that the detecting probability is only related with the size of deviation and isn’t related with direction of deviation.