Abstract: Mammal species under several realms are confluent in Sichuan and Chongqing,with very affluent biodiversity,and large amont of endemic components. On ecological sub-region as units, indices were chosen from coefficients of space accommodation and genetic potential, and the five indices were about distribution,indigenousness,specific model and economic value. The system was drawn up for quantitative evaluation of vulnerability degree (value VC),and 223 ferine species in Sichuan were marked according to grades. The results showed that Sichuan hairy-tailed dormouse bore the highest VC of 0.9,and the next was the giant panda. Mammals with the lowest VC by grading were mostly murines of Rodentia and bats of Chiroptera. Afterward,coefficients under threat were classified by cluster analysis through strict mathematic method for 7 orders separately,so as to obtain species with the maximum and minimum values of 5 indexes among each order. It was found that a number of species bearing highest VC in order were not necessarily primary in sequence made by the clustering, so they didnot occupy extremely urgent location in preferential conservation. It was testified by F test that the occurrence of species was not correlated, and ingredients of realms were not divided in terrain clearly. It was discovered that 7 realms survived and coexisted in Sichuan intricately, and formulas about membership function were deduced according to scores of each mammal, so as to judge which realm they belonged to, i. e. Palaearctic, Oriental, Palaeotropical or etc. Palaearctic was formed during lower series of Triassic System, Oriental in medium series of Jurassic System, and species quantity in these two realms were the most. After splitting of the Gondwana, realms came into being in turn. Neoarctic had emerged at Younger Dryas posterior to Miocene Series (N₁), whereas Neotropical within Q. It was put forward that mammals for decision of Quaternary period were palm civet, civet cat and etc. Ratio of Quaternary species was the largest in Lagomorpha, and Insectivora was secondary. Differentiation evolution of giant pandas and lesser pandas had proved that icecap of Pleistocene glacier had not occurred in mountain areas around the Sichuan Basin during Quaternary, and Neoarctic happened later than ancestors of red pandas were born. Gradual oscillation of climate in Younger Dryas was watershed of evolvement from Eutherian species to Cainotheres. Oriental species differentiated, processed among 4 sections and were reflected in Sichuan.