The Mashan khondalite series in eastern Heilongjing Province,China, was regionally metamophosed during the late Archeau to early Proterozoic and subsequently underwent migmatization. Two zones of progressive metamorphism are recognized: the granulite facies zone and the amphibolite zone. Studies on their textural relation and metamorphic reaction reveal that the metamorphic rocks in the granulite facies zone have undergone three episodes of metamorphism from lower amphibolite facies to upper amphi- bolite facies, and finally to granulite facies. At the stage of lower amphibolite fades, in high-aluminium and alkali- depleted rocks, pyrophylliite transferred directly into prismatic sillimanite, whereas in normal pelitic rocks, chlorite and muscovite formed during low grade metamorphism transferred into andalusite and biotite. The P-T condi- bona of the stage are inferred to be 530-5600℃，(3-4)×108Pa. At. the stage of upper amphibolite facies, muscovite in high.-potassium metapelites was converted into sillimanite and potash feldspar in the presence of quartz. The P-T conditions of this stage are 600-7000℃，(4-5)×108Pa. The graaulite facies metamorphism is marked by the appearance of hypersthene of metamorphic origin in mafic rocks and some of pelitic rocks. The "peak" metamorphic temperature and. pressure of this stage are 800- 8500℃，and 7.4 × 108Pa respectively. After the granulite facies metamorphism, with the crustal thickening caused by the folding or thrusting during regional metamorphism, isostatic uplift of tlae crust resulted in the formation of cordi'erite from the conti- nuous reaction of sillimanite+garnet+quartz .P-Tconditions of the stage are calculated at 800℃，and (4.5-5)×108Pa. The temperature and pressure of migmatization stage determined by Bi-Ga and Ga-Pl-Sil-Q pairs are 700-750C，and(3.5-4)×lO8Pa respectively. Mineral assemblages and metamorphic reactions of other rock series at different stages are also discussed. On the basis of the above discussion, a possible P-T-t path of the Mashan khondalite series in the regional metamorphism is given in this paper. The similarity of the P-T-t path of metamorpb:ism of the Mashan Group to that of typical orogenic belts and its uniform P-T conditions on a large scale suggest that the metamorphism of the Mashan khondalite series occurred in a regional orogenic background.