Two phases of sinistral strike-slip ductile shear belts occur on the eastern margin of the Dabie orogenic belt.A muscovite 40Ar/39Ar plateau age of 128 Ma was obtained from mylonite in the later ductile shear zone. Three muscovite samples separated from mylonites of 3 localities in the earlier ductile shear belts yield 40Ar/39Ar plateau ages of 192.5±0.7 Ma, 189.7±0.6 Ma and 188.7±0.7 Ma, respectively. They are interpreted as cooling ages of the earlier sinistrai strike-slip deformation. It is suggested that left-lateral displacement of the Tan-Lu fault zone started in a late stage of the collision orogeny in the Dabie-Sulu orogenic belt between the North and South China plates. Therefore, the earlier Tan-Lu fault zone was syn-orogenic strike-slip tectonics.The fault zone was used again for sinistral displacement during tectonic activities of peri-Pacific regime in Early Cretaceous. It is proposed that the fault zone occurred as a transform fault during the orogenic process.