Abstract: The suture zone of Longmu Cuo-Shuanghu is the east-west intermittent and unequal size of rock mass of granite, according to the regional geological survey at the scale of 1∶250000 of results, which belongs to Early Jurassic-Late Jurassic LA-ICP-MS Zircon U-Pb dating for two sample granodiorite in Naru area of Shuanghu, Tibet, obtaining 215.1±1.8Ma, 217.0±1.5Ma age, belonging to late Triassic. The geochemistry research showed that the granodiorite belongs to partial aluminium-peraluminous high potassium calc alkalinegranite, light and heavy REE fractionation is obnious, the high field strength elements Nb, Ta, Ti strongly depleted. Formed in the Longmu Co-Shuanghu paleo-Tethys ocean closed after the collision of the late stage of post collision extensional environment, the Longmu Co-Shuanghu suture zone represents the northward subduction of Tethys oceanic lithosphere, after the subducting slab break off, upwelling of the asthenospheric material, reduced pressure and rise temperature, spur the partial crust material melting, the granodiorite is partial melting of the crust material.