Selective laser melting (SLM) can directly produce personalized medical implants with complex shapes based on CAD models. The paper presents an investigate on the evolution of microstructure and mechanical properties of biological pure titanium (TA1) from SLM to subsequent heat treatment. The results show that the SLMed TA1 alloy possess needle-like martensite a′ and retained prior-β columnar morphology along the building direction. After heat treatment, recrystallized equiaxed a grains are formed and the reduced porosity was found due to pores volume decrease or pores closure. In addition, the precipitations of fine TiFe and TiO₂ were observed along grain boundary or within grains in the samples treated by vacuum annealing at 800 ℃. They precipitate selectivity along the grain boundaries with different character. The subsequent heat treatments, especially vacuum annealing, significantly improve the mechanical properties of the SLMed TA1 samples, which is ascribed to combined effects of porosity decrease and the precipitation of TiFe/TiO₂ phase upon annealing.