Early Carboniferous volcanic rocks in East Kunlun Mountains are distributed along Mid-Kunlun deep fault zone and consist mainly of basalts overlain by andesites and dactite. They were formed sequentially in setting of mid-cean ridge, ocean island and island arc. The mid-ocean ridge basalt has lower K2O, P2O5,SiO2, REE, FeO*/MgO and LREE/HREE values,and higher CaO, FeO*and MgO contents than the island-arc basalt. The ocean island basalt is characterized by highest TiO2and lowest K2O contents, but its REE and LREE/HREE values are between values of the other two sorts of basalts. The study on the tectonic setting of the volcanic rocks shows that the Mid-Kunlun suture was dominantly in“spreading”state in Early Carboniferous, resulting in the formation of mid-ocean ridge basalt and ocean island basalt, and then evolved into“closing”state, giving birth to island-arc basalt, andesite and dacite at the end of Early Carboniferous. The identification of the ocean-ridge basalt is important to the understanding regional tectonics and its evolution.