Abstract: The subduction of the Neo-Tethyan Ocean and the collision of the India-Asia plate resulted in the distribution of large amounts of igneous rocks in the Gangdise tectonic belt in Tibet, whose age remains in dispute, and the exact age and tectonic significance are important for revealing the information of plate movement. In this study, the U-Pb isotopic age of zircon samples from the Dianzhong Formation in Shongong area was determined, and the geochemical analysis of major elements, trace elements and REE was carried out. The result indicates that the age of igneous rocks at the bottom and top of the Dianzhong Formation is 65.37±0.58Ma and 57.42±0.20Ma, respectively. The distribution curve of REE shows the rightward form of LREE concentration and HREE loss, with obvious negative Eu anomalies. The average ratio of K₂O/Na₂O, Rb/Sr and Nb/T is 1.57, 1.78 and 13.28, respectively. The Dianzhong Formation igneous rocks in Shongong area are enriched in Rb, Th, U and Pb and depleted in Nb, Ta and Ti. The authors hold that the igneous rocks of the Dianzhong Formation were formed by magmatic mixing of the mantle and the crust in different proportions in the background of subduction collision, which may indicate the subduction of oceanic crust caused by the closure of the Neo-Tethyan Ocean.