Geochronology and geochemistry of dioritic gneiss in the Lianggehu region, Qiangtang Basin is examined for the first time so as to determined its age and genesis. Results show that dioritic gneiss is composed of a suite of diorite and gabbro-diorite. Zircon occur as long columnar euhedral and hypidiomorphic crystals with well-developed tight oscillating zonal structure, indicating magmatic origin. LA-ICP-MS U-Pb zircon dating of three pieces of dioritic gneiss samples are (220.48±0.49)Ma、(217.9±0.51)Ma and (219.98±0.49)Ma respectively, with an average value of (219.45±0.50)Ma, indicating that dioritic gneiss was formed at the age of Triassic Carnian. The SiO2, MgO and Al2O3 contents of dioritic gneiss range from 55.17 to 58.61%,1.71 to 2.74% and 20.18 to 21.43% respectively. The dioritic gneiss are characterized by high Mg# value (0.38~0.53) , Na enrichment (Na2O/K2O= 1.17~7.38), strong LREE and LILE enrichment , obvious negative anomalies of HFSE, and no Eu anomaly. The isotopic (87Sr/86Sr)t and εNd(t) values of dioritic gneiss vary in range of 0.70868 to 0.71024 and -3.4 to -2.8 respectively. These characteristics combined with lead isotopic parameter indicate that the magmatic source of dioritic gneiss is derived from lithosphere mantle modified strongly by the continental crust.