Abstract: In some literatures, the mineral assemblages of different metamorphic grades of Liaohe Group are regarded as the mineral assemblages of different stages. Actually, they are the results of different sites, times and phases. They just coexist spatially, but not temporally. The pressure-temperature condition curves of mineral associations of different metamorphic grades should not be served as the P-T-t paths. In fact, this kind of curves is field metamorphic gradient, which intersects the P-T-t path with large angle. Therefore it is inappropriate to discuss the metamorphism evolution of Liaohe Group with field metamorphic gradient instead of P-T-t path.