Ultrasonic P wave velocity (Vp) and quality factor (Qp value, on behalf of attenuation) in pyroxenite were presented as functions of pressures (0.3-3.0 GPa) and temperatures (20-1170° C). The experimental results show that Vp and Qp depend upon pressure and temperature. Vp and Qp in pyroxenite increase more rapidly at the pressure 0.3-1.4 GPa than those at 1.4-3.0 GPa. As the temperature rising from 20° C to about 1170° C at the pressure 3.0 GPa, an almost linear decrease up to 11% in Vp was observed, and Qp drops from 243 at room temperature to 68 at 1170° C with decreasing 72%. The experimental data indicate that the pressure and temperature induced fabric changes and frictional sliding and dislocation in pyroxenite play a key role in wave propagation in rocks.