Based on a study of Mapeng rock mass in the Shihu gold deposit, this paper made a systematic determination on the petrochemical composition, trace elements and rare earth elements of the porphyritic granite, granodiorite and quartz diorite respectively. The Sio2 of rock mass averages 67.77％, slightly lower than that of Wang’anzhen quartz syerite of Zijingguan in the northeast, which belongs to the same structural magmatic belt. The total REE of Mapeng rock mass are relatively high, which range from 136.41×10-6 to 167.45×10-6. The REE distribution pattern inclines toward the right. The LREE/HREE value ranges from 12.50 to 18.75,averaging 16.07. It is characterized by obvious enrichment of light REE and depletion of heavy REE. From characteristics of petrology, trace elements and rare earth elements of Mapeng rock mass, the authors have reached the conclusion that the Mapeng rock mass is I_type granite. 