With study on the Carboniferous-Permian strata in Daxinganling and its adjacent areas, this paper introduces their distribution, rock association, fossil assemblage etc. Based on the Paleozoic plate tectonic movement of this region, the author gives a biological paleogeographical division, i.e. the northern part of the region belongs to the Xingan sub-province, Junggar-Xingan province of Boreal Realm, to be characteristic of the fauna of cool water type;while the southern part is assigned to the northern marginal sub-province, North China province of Tethyan Realm, characterized by the fauna of warm water type. The mixed fauna of cool and warm water fossil types are distributed in some places between the Siberian plate and the North China plate during Early-Middle Permian.