Abstract: The investigation of interspecific relationship between the Great Tit Parus major and willow Tit Parus montanus was carried out at the Qilian Mountain,from April to Juny of 1984,from May to June of 1985 and at the Xinglong Mountain from March to May of 1986 in Province Gansu.The paper deals with the interspecific relationship between the Great Tit and Willow Tit in the selection of habitat,foraging niches and the analysis of food.In the overlap areas of geographic distribution,overlap value of niche between the Great Tit and the Willow Tit is lower in the altitude of habitat.The Great Tit habits at an altitude of below 2370 m,and prefering chiefly to aspen-birch community and artificial old-age popular community,but the willow Tit habits at an altitude of over 2300 m,prefering more greatly to the mixed community and mountain aspen-oak community.There are certain overlap in their habitats,but the overlap value is lower.In the overlap among 4 dimensions of foraging niches between two species of tit,there is lower overlap value of niche in the dimensions selecting the kinds of trees,but the overlap value of niches is all greater in the others.Between two species of tit there is certain overlaps in the trophic niche,and overlap value of size of food is more great.In the course of evolution and development,through ecological separation between two species does not take place.