Abstract: Guoganjianianshan Permian ophiolite is an important discovery in Longmu Co-Shuanghu plate suture zone recently. According to detailed field geological investigation, we found that Guoganjianianshan Permian ophiolite outcroped extensively and included cumulate gabbro, mafic dyke swarms and basalt. In this paper, SIMS U-Pb dating was carried on the zircons of the gabbro dyke of Guoganjianianshan ophiolite. The dating results show that this ophiolite was fromed in Early Permian (272.9±1.8 Ma), which means that a great tectonic event happened in Early Permian. All the research results above have great significance in exploring and establishing the tectonic evolution space-time model of Paleo-Tethys ocean.