Three orthophyre samples were collected from the Jiangcuo iron deposit, which is located 100km northeast of Baingoin County. Petrographic and geochemistry study shows that the orthophyre has a SiO2 content of 59.55%~62.61% (ave. 61.52%) Na2O content of 9.31%~10.01% (ave. 9.74%), K2O content of 0.107%~0.12% (ave. 0.113%), with the Rittman index ranging from 5.16 to 5.36. This indicates that the rocks belong to sodic alkaline rock series. Alkaline rock of this kind was discovered for the first time in the Ban’ge area in the middle part of the BagongNujiang suture belt. Zircon LA-MC-ICP-MS U-Pb dating yields an age of 170±24Ma at Yanshannian MidJurassic period. Comprehensive study of regional geological comparison shows that the set of orthophyre should be the product of immature island arc of of the BangongNujiang basin at early stage of subduction.