Aedes triseriatus(Say), the eastern treehole mosquito (Diptera: Culicidae), is an important medical vector transmitting the LaCrosse encephalitis(LAC) and West Nile Virus, distributed in north America, which ever caused the LAC epidemic in east and central America. With the medical-vectors intercepted data of Sino-North America trade at port, it was confirmed that it is possible for A. triseriatus to invade China by cargoes, imported timbers, containers, etc. The life cycle of A. triseriatus is closely related to the temperature and humidity. Three models were used. CLIMEX model was used to analyze the possible colonized area of A. triseriatus in China, the epidemic risk of LAC encephalitis transmitted by A. triseriatus was analyzed by MaxEnt model, and ArcGIS9.2 was used to analyze the model results. The purpose of this research is to establish a superposition model on the risk analysis of medical-vectors. The result shows that the eastern treehole mosquito could colonize in China. The high risk areas of LAC encephalitis are in Yunnan, Sichuan, Guizhou, Chongqing, Hubei, Anhui, Jiangsu, Zhejiang, Jiangxi, Hunan, Guangxi, Guangdong, Fujian, Hainan, Taiwan; South of Shanxi, Henan, Shandong; Southeast of Liaoning provinces; The medium risk areas covers most of Shanxi, Shaanxi, Hebei, Tianjin, Jilin, Heilongjiang; South of Xizang, Gansu, Ningxia, Qinghai; North of Sichuan, Liaoning, Shandong, Henan, Middle of Neimeng and parts of southwest Xinjiang provinces. The low risk area includes north of Xizang, Ningxia; South of Qinghai; Middle of Gansu, Neimeng, North of Ningxia, parts of southwest Xinjiang provinces.