Abstract: The exotic blocks on northern slope of the Himalayas described in present paper are the relics of rock blocks transported in a long distance in the process of subduction and collision. Genetically, they are distinguished from both klippe and nappe as well as from melanges and olistostromes because they are not the result of mixing with allochthonous rocks. The characteristics of exotic blocks on northern slope of the Himalayas are presented as follows:1. They distribute on the southern side of Yarlun-Zangbo Jiang suture, in a narrow longitudinal belt on the northern border of the Indian plate.2. These blocks are composed mainly of Permian brittle limestones.3. Their gentle occurrence and the overturning of drag folds to wards the south indicate that these exotic blocks were transported from the north.4. The source of these exotic blocks is quite different because, faunistically, they reflect different sedimentary environments. Basing on the characters of faunal assemblage and lithologic correlation, the origin of these exotic blocks may be distinguished into three types: the subduction, the obduction and the compression. They are all formed by the northward subduction of the Indian plate down the Eurasian plate and the collision between them.