Abstract: Nineteen species of intestinal parasites, including 7 species of nematode, 8 protozoa,2 cestodes and 2 trematodes were discovered in 18 468,people with an infection rate of 80.6% from 9 counties of 4 types of topography in Sichuan. The statistical analyses showed that the figures of infection rate, parasite species and intensity of infection were significantly different among areas of diverse topography, i. e. the figures were elevating in the ascending order in areas located at west Sichuan plateau, the surroundings of mountains of Sichuan Basin, hilly plain and hilly region.According to G test and binomial distribution analysis based on 2743 families with complete data of fecal examination, the positive infections of Asccris lumbricoides, Trichuris trichiura, hookworm, Giardia lamblia, Blastocystis hominis and Entamoeba coli showed evidence of family clustering due to the identical environmental sanitation and habits in daily life.