Abstract: Titanium alloys are widely used in aerospace and other fields due to their low density, high specific strength, and high corrosion resistance. In order to study the effect of heat-treated microstructure on the mechanical and corrosion properties of Ti-6Al-4V alloy additively manufactured (AM) by laser powder bed fusion (L-PBF), three sets of samples are prepared: as-built state, 650℃/4h stress relief heat treatment, and 800℃/2h annealing heat treatment. A systematic study is carried out by combining microstructure characterization, XRD phase analysis, TEM observation, tensile testing, and electrochemical testing. The results show that the as-printed sample forms a fully α′ martensitic structure due to rapid cooling, exhibiting high strength (ultimate tensile strength of 1260 MPa) but limited plasticity (elongation of 13.06% ) and excellent corrosion resistance (passivation current density of 1.03×10?? A·cm?2). The 650℃/4h heat treatment promoted partial decomposition of the α' phase, resulting in a slight decrease in both tensile strength and total elongation (1141 MPa and 13.51%, respectively), but a significant deterioration in corrosion performance (passivation current density increased to 1.66×10?? A·cm?2). The annealing treatment at 800℃ facilitates the transformation of α' martensite to α/β dual-phase lamellar structure. While reducing tensile strength to 990 MPa, it increases the total elongation to 17.51% and partially restoring the corrosion performance (passivation current density of 1.23×10?? A·cm?2). This study confirms that post-AM heat treatment can simultaneously alter the strength-plasticity balance and corrosion behavior of L-PBF processed Ti-6Al-4V alloy by regulating the degree of martensitic decomposition, thereby achieving overall performance improvement of the alloy.