Abstract: The tectonic location of Late Carboniferous porphyritic granodiorite of Heihongshan area in Beishan region belongs to Beishan-Tianshan orogenic system and Ejina-Beishan arc basin system, but without reliable zircon U-Pb dating report. On the basis of the detailed internal structure analysis of zircons from the porphyritic granodiorite using the technology of cathodoluminescence, the authors conducted isotope age analysis using LA-ICP-MS zircon U-Pb dating method. The result shows that porphyritic granodiorite formed at 312.1±3.2Ma. Geochemical study shows that porphyritic granodiorite belongs to medium potash-calc alkaline, quasi-aluminous granite system, being I type granite. It has characteristics of light REE enrichment and characteristics of enrichment of Rb, Th, K, Hf and depletion of Ta, Nb, Ti, P. It formed in a pre-collision tectonic environment. Combined with regional geological background, It is considered that ocean basin, represented by Hongshishan-Baiheshan-Pengboshanophiolite, should not have been closed in Late Carboniferous period.