Abstract: The "Archean metamorphic rock" from Fuxin area in Liaoning Province is the lowest part of Archearn terrene in the northern margin of North China plate, which is composed of discontinuous supracrustal rocks, TTG series and some other plutons. The basic rock type of this metamorphic rock includes:hornblendite, pyroxenite, amphibolite,granulite, charnockite, gneisses and little magnetite quartzite. Its main diagnostic metamorphic minerals are garnet, orthopyroxene, clinopyroxene, hornblende, plagioclase and quartz.Petrographic studies identified that three metamorphic reactions occurred in different stages of metamorphism, and they are in good agreement with the transformation of the mineral phase.Combined with the limits of geological temperature and pressure, the IBC-type PTt evolution path of intense metamorphic thermal event at the end of the Archean Eon has been concluded in this paper, which is the near isobaric cooling process.And then, it's inferred that the metamorphic thermal event was formed in a large number of low-pad supports of magma, which is accompanied by the tectonic setting of the deep crust.