The Tianshan Mountain is believed to be a typical intracontinental mountain belt; the Tianshan Mountain was formed during tectonic amalgamation of the Tarim and Tianshan block and the Siberian carton in Late Carboniferous-Permian period. A series of basaltic extrusive and intrusive units were emplaced primarily in Late Cretaceous-Plaeogene sedimentary rocks in Tuyon basin and its adjacent area, South Tianshan Mountain. Geochemical data of basalts show low Sr and Pb isotopic values and relative high Nd values (87Sr/86Sr=0.703554~0.703884;143Nd/144Nd = 0. 512838 ~ 0. 512904;206Pb/204Pb = 18. 0063 ~ 18.4720;207Pb/204Pb=15.4411~15.5060;208Pb/204Pb=37.8072~37.9290). The data of major elements, trace elements and rare earth elements indicate that these basaltic rocks are similar to alkaline basalts of Hawaiian type oceanic silands. According to Nd/Sr isotopic ratios, the Tuyon basalts might have originated from low_grade melting of a source (mantle plume) similar to that beneath the Hawaiian Islands. In Tuyon basin and adjacent areas, several fields of Cenozoic alkaline basaltic magmatism may be related to the Cenozoic activity of mantle plumes.