Commercially pure (CP) titanium having hexagonal structure exhibits unusual anisotropy and asymmetry at room temperature. Activation of various slip and twinning is known to cause the complex deformation behavior of CP titanium. In this study, microstructural variation obtained by in-situ tensile EBSD analysis and observed slip traces were compared with the calculated results by crystal plasticity finite element analysis. Also, the slip deformation and twinning of each grain with various orientation was investigated quantitatively. 3D micromechanical models were generated and the material parameters were calibrated using the macroscopic behavior under various loading conditions. The deformation modes quantitatively analyzed in which values of critical resolved shear stress (CRSS) is in order, prismatic slip < basal slip < tensile twin < pyramidal slip. Slip trace analysis confirmed that prismatic slip is dominant deformation mode regardless of oxygen content, and predicted twin variants by crystal plasticity model are in agreement with results from the EBSD analysis.