The ductile shear belt exposures in Mangsan Reservoir-Diaoluoshan Tree Farm-Xinglong area successively with its strike being north-east. The lithology is tectonic gneiss and granite of mylonitization, and main minerals are composed of feldspar, quartz and biotite. The rock develops as "S-C" fabric, "" style gyral porphyroclast system, mica fish etc. The tectonic fabric indicates right handed shearing movement. According to mineral component and deforming feature, the deforming environment should be low amphibolite facies, which belongs to the product emplacing across the shear zone and transforming synchronously. This time we got 284.3 ± 1.3 Ma and 265.9 ± 1.3 Ma by laser ICP-MS for zircons from Mangsan Reservoir and Diaoluoshan Tree Farm. The founding of ductile shear belt and its geologic age plays an important role in the intensive study of construction-magma function of Hainan Island.