Abstract: The Aretuobie monzonitic granite is located to the south side of the Mayinebo suture zone. It shares some characteristics of the A-type granite, such as high alkali and low alumina. However, comparing with typical A-type granite, it has relatively high MgO and CaO and low SiO₂. In trace elements, their total REE ranges from 277 ppm to 326 ppm and the ratios of LREE/HREE are bet ween 5.6 and 6.9. Negative Eu anomalies (δ_Eu=0.4-0.6) are present ed in the REE pat terns. The rocks are enriched in incompatible elements and havev ariable Sr, Ba, Nb, P and Ti troughs in their trace elements distribution patterns. Isot opically, they have low initial Sr ratios (0.70048-0.70547) and positive initial Nd values (2.6-3.2). Collectively, we suggest that the Aretuobie pluton was derived from partial melting of a juvenile maficlo wercrust in a postorogenic extensional background.