Gneiss dome is an important structure resulting from magmatism, metamorphism and deforming during orogeny. A gneiss dome is first reported closely along the northern part of the Xianshuihe sinistral strike-slip fault zone in the Songpan-Ganzi block. It is composed of undeformed granite in the core and foliated granite in the edge, whose lithology close to the fault has been mylonitized. LA-ICP-MS U-Pb dating shows that the undeformed granite formed at 14.51±0.82 Ma and the ages of foliated granites are 14.39±0.23 Ma, 4.25±0.34 Ma and 18.2±1.3 Ma，which indicates the gneiss dome formed at 18~14 Ma. The U-Pb age of mylonite and granite vein in the Xianshuihe shear zone are estimated 14.57±0.34 Ma and 16.73±0.97 Ma, respectively. These ages show a close relationship between the formation of the gneiss dome and the shearing of the Xianshuihe fault zone that the former results from partial melting and bulging of the upper crustal rocks under the shearing of the latter. And in return, the melting promoted the southeastward spreading of the Xianshuihe fault zone, resulting in the formation of the Red River fault along its southeastern part at 11~10 Ma. Meanwhile, they accelerated the clockwise rotation of the Chuandian block, coordinated the eastward motion of the materials in the eastern Tibet and boosted the thickening of the upper crust and subsequent mountain building and river incision. These resulted in rapid cooling of the gneiss dome with a rate of ~61℃/Ma and ~146℃/Ma at 12~5.5 Ma and 4.4~3.1 Ma, respectively.