Abstract: North Qilian (NQL)-North Altun (NAT) HP/LT metamorphic belt and North Qaidam (NQD)-South Altun (SAT) UHP metamorphic belt are located in the northern and southern sides of Qilian-Altun orogen, respectively. NQL-NAT HP/LT metamorphic belt mainly consists of blueschist, low-temperature eclogite and high pressure metasedimentary rocks. Eclogites were formed under the metamorphic conditions of 420~570℃ and 2.1~2.6GPa, and at 510~440Ma. The lawsonite-bearing eclogites and carpholite-bearing high pressure metasdimentary rocks indicate the existence of cold subduction zone gradient and cold subduction brought a large amount of H2O to the deep mantle in the Early Palaeozoic times. HP/LT metamorphic belt is associated with ophiolite, subduction-accretion complex, island arc and back-arc basin, suggesting that the NQL is a typical Early Paleozoic acccretion orogenic belt. In contrast, the NQD-SAT UHP metamorphic belt is composed of eclogite, garnet peridotite, high pressure granulite and continental orogneiss and paragneiss. These rocks were subjected to UHP metamorphism at T>700℃ and P>2.7GPa. Geochronology suggests that the UHP metamorphism occurred at 500 to 420Ma, and the protolith age of eclogite at 850~750Ma, related to a Neoproterozic continental rift origin. Field relationship, petrology and geochronology suggest that the NQD-SAT UHP metamorphic belt was resulted from the deep subduction of continental crust rocks. In the NQD-SAT UHP metamorphic belt, UHP eclogite and HP granulite produced in different thermal environments at same time, suggesting a “paired metamorphic belt” related to continental subduction and collision, and also implying that the NQD-SAT is a typical Early Paleozoic collision orogen. These data indicate accretion orogeny and collision orogeny developed synchronously in two side of Qilian-Altun orogenic belt, and formed a composite orogen as a result of different type of orogeny. HP/LT metamorphic belt and HP/UHP metamorphic belt control the orogenic type and mechanism of Qilian-Altun orogen in Early Paleozoic time.