The TC6 alloy microstructure and tensile properties were investigated by different heat treatments. The results reveal that with the cooling rate increasing, the content of primary α phase, size and thickness of secondary α-phase sheets decrease, the intensity increases, while the plasticity of air cooling is better than that of oil and water cooling. Aging temperature increase makes the primary α phase grow up, and the secondary α phase field reduces, while the thickness increases, meanwhile intensity decreases and plasticity increases. Aging time increase makes the thickness of the secondary α phase larger and even globalization, but there is little change in strength and plasticity. After triple heat treatment, the thickness of the secondary α-phase sheets are larger than that of single-stage solid solution, and the samples elongation is improved, while intensity is decreased by 100 MPa.