A systematic study on determining the influence of Ti addition on the microstructure and mechanical properties of a Nb-microalloyed crack arrest steel has been carried out. Optical, electron microscopy, X-ray diffraction, transmission electron microscopy, and electron back-scattered diffraction were applied to characterize the microstructure and phase transformation.. The microhardness, Tensile strength and Charpy impact energy were evaluated. Based on these results, the effects of Ti and aging treatment on the microstructure and mechanical properties are discussed. This work was supported by the NSFC Funding (51371062 and U1460102), NSFHLJ (ZD201411), the Project for Innovative Talents of Science and Technology of Harbin (2014RFXXJ006), and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Heilongjiang Province.