This study was carried out to evaluate the microstructures and mechanical properties development on additive manufactured pure Ti for orthopedic implants. Selected laser sintering (SLS) as an additive manufacturing process was introduced, and pure Ti powder with a size of 50-60 microns as a material was selected. In order to investigate the microstructures development by different heat-input, additive manufacturing was conducted from 0.2 to 1.6 J/mm2. For these materials, the grain boundary characteristic distributions (GBCD) such as grain size, misorientation angle, orientation and shape were evaluated by electron backscattering diffraction (EBSD) method. In case of mechanical property, Vickers microhardness as a classical method was introduced. As a result, increase in heat-input led to the increase in grain size form 4 microns to 12 microns, accompanying with the change of grain shape. Accordingly, lath typed grains were gradually increased in accordance with increased heat-input. In addition, Vickers microhardness was significantly increased from 218 Hv to 358 Hv with elevated heat-input, which was attributed to the changes in grain shape. These changeable shapes could be occurred by phase transformation due to the increased heat-input. In this study, we discuss the aspect of microstructures and mechanical properties development correlated with the phase transformation in terms of difference in heat-input.