Abstract: There are two methods of Studying spatial distribution patterns for insect population．They are：the method of frenquency distribution and index of distribution patterns．We suggest a new method in this paper，I.e. correlation coefficient method．It’s more simple than other two methods and has a wider-range of application．As a result of practice of the method for egg-masses and cocoons of the pine caterpillar(Dendrolimus punctatus Walker)，cocoons distribution fits to the geometric distribution and the Weibull distribution．While r is higher in the geometric distribution than in the Weibull distribution．The egg-masses distribution fits to the Poisson and geometric distribution and r is higher in the geometric distribution than in the poisson distribution．In conclusion，the probability distribution of both egg-masses and cocoons of the pine caterpillar fits to the geometric distribution quite well．