The evolution of grain boundary character distribution (GBCD) in the CoCrMo alloys processed by SLM and post-heat treatments (aging and solid solution) has been investigated by the electron backscatter diffraction (EBSD) and transmission electron microscope techniques. A high fraction of sigma 3(n)(n = 1, 2, 3) grain boundaries and the corresponding clusters occur in the solid solution-treated samples at 1150 degrees C, which indicates GBCD optimization is somewhat realized. The coherent and incoherent sigma 3 boundaries were distinguished via the single-section trace analysis method based on EBSD measurements. sigma 3 boundaries in the SLMed and aged samples were determined as incoherent, while those in the solid solution-treated sample are coherent. Regular epsilon precipitation did not occur in the solid solution-treated samples as in the aged samples. Instead, stacking fault bands associated with coherent sigma 3 twin boundaries are dominant. It suggests that post-heat treatment has a significant influence on the GBCD, especially the sigma 3 grain boundary characteristics.