Abstract: The microstructure of commercial pure titanium processed by equal channel angular pressing(ECAP)at room temperature was studied by using optial microscopy and TEM.The functions of three deformation mechanisms including slipping,twinning and grain turning during the plastic deformation at room temperature were discussed.The results show that sliding and twinning were the main deformation mechanisms of the commercial pure Ti during ECAP deformation at room temperature.And grain turning was another important mechanism to coordinated the large grain deformation and improve the ductility of commercial pure titanium.Dynamic recrystallization was the important coordination mechanism in plastic deformation.