Abstract: This paper statistically analyses the spatial probabilistic characteristics of random variables in geotechnical problems. Both the iteration process to determine the parameters for a beta probability density function and the empirical formula to simplify this iteration are presented. Therefore, the estimation of the lxxmds of random variables is handled efficiently and the applicability of the beta distribution in reliability analysis is illustrated. Certain other types of distribution are chosen to fit the same random sample for comparison and the results prove that the beta distribution is superior to others.