Objectives: Based on Petrology study and method of zircon LA-ICP-MS ages and geochemistry of Intrusive Rocks in Qitaidaban Area，to dicuss the age of the Paleo-Tethys closure and to explore It’s direction subduction． Methods:Zircon trace element analysis by the Northwest University of State Key Laboratory of Continental Dynamics completed，this instrument was the United States Agilent Company produced Agilent7500atype quadrupole mass spectrometer and Germany Microlascompany’s Geolas200Mtype laser ablation system．Calculating rhe zircon age used the standard ziecon 91500 as the external standard，elemental content used NISTSRM610 as an external standard，29Si was calibrated as an internal standard element．Data acquisition and processing used GLITTER，And used the Andersen to test the data for ordinary Pb correction，Ages calculation and concatenation drawing used ISOPLOT． Main quantity elements，rare earth elements，trace elements are completed by Industry Analysis test center of No．203 Researth Institute of Nuclear．Main quantity elements and Trace elements ( such as P, Ba, V, Cr, Rb, Sr, Zr, Sc) was analyzed by XRF method (FeO was analyzed by volumetric method)，this instrument was an Axios Xray spectrometer manufactured in the Netherlands; all rare earth and trace elements such as Co, Ni, Nb, Hf, Ta, Th, U by ICPMS analysis，This instrument was an XSERIES2type ICPMS manufactured by Thermo Fisher Scientific. Results: The intrusive rocks of Qitaidaban area were composed of tonalite, quartz diorite and granodiorite. LAICPMS zircon UPb LA ages results show that their were 2147±2 Ma、2113±33 Ma and 2106±28 Ma，their belongs to Late Triassic. Geochemmical analysis shows that：SiO2＝5896%～6752%，Al2O3＝ 1637%～1479%，CaO＝341%～525%，MgO＝147%～342%， K2O + Na2O )＝436% ～64%，They belong to calcalkaline series. ∑ REE = 10127× 10-6～27104 × 10-6，REE fractionation is obvious ( LaN / YbN average was 1069 )，Which whith Eu is obviously abnormal．LILE(Rb, K and Th)are quite enrichment，but relative loss Ba；Strong loss of high field strength elements( HFSE) such as Nb, Zr, Hf, Sr, P, Ti． Conclusions: Analysis of the intrusive rocks in the study area，results show that they are formed in the continental margin arc environment of Non Itype granite，the material derived from the crust source for amphibolite facies basalt, involved in a small amount of mantle material．According to the genetic types of the intrusives and combined with the regional tectonic environment evolution．in the Late Triassic，the southern margin of the PaleoTethys occurred continuously underthrust from NE to SW， began to ocean—continent transition. At the same time，the intrusives was produced under such mechanism．