By taking the pressure effect into account in the free volume evolution, the yield asymmetry between tension and compression of metallic glasses under different temperatures is investigated. The yield strength in MGs with a (T/Tg)1/2 temperature dependence is obtained for both tension and compression. The pressure - sensitive factor is derived to be a constant ～ 0.1 within a broad range of temperatures. Furthermore, it is revealed that, the declining effect of pressure on the free volume evolution causes a weaker tension - compression asymmetry with increasing temperature. The significant structural relaxation at high temperature slows down the free volume evolution and hinders the sharp yield. These results improve our understanding of the underlying mechanisms of the yielding and its asymmetry between tension and compression in MGs.