After contrasting the features in petrology and petrochemistry between middle and southern basalt samples from the Okinawa Trough, we find both middle and southern basalts belong to subalkalic series, and the former vest in tholeiitic and calc-alkalic series, the latter mainly calc-alkalic series. According to petrochemistry characteristics, middle basalts are named quartz tholeiite primarily and southern ones olivine tholeiite. The magma of the middle and southern Okinawa Trough basalts are both originated from partial melting of the mantle rock underground, while the source mantle are uneven and magma evolution degree are different. Middle samples' source are close to transitional mantle and crystallization & differentiation have a higher degree; however, southern ones normal or prosperous mantle, and a lower degree crystallization & differentiation. Two area basalts have also experienced assimilation & contamination of different degrees. The differences between middle and southern basalts from the Okinawa Trough in petrology and petrochemistry are directly relative to their uneven source mantle and magma evolution at different degree. The tectonic settings of the basalts are transitional between MORB (tensile) and IAB (compressive), still representing the earlier stage of magma activities in the Okinawa Trough.