The microstructure and mechanical property of TA15 titanium alloy by Directed Energy Deposition with Hot Isotatic Pressing were analyzed in different building directions. The samples with different directions had different microstructures, which in 0° direction was composed of a number of α and a large amount of acicular αʹ, and there was a certain amount of equiaxial α-phase in 45° direction, and which in 90° direction was a typical basket-weave structure and composed of α + β phases. Micro-structural evaluation promoted the improvement of ductile property. Among three directions, the tensile strength and the yield strength of 45° directions were the lowest, yet its elongation was the highest. HIP process had a significant influence on the mechanical properties of DED TA15 titanium alloy. It made the strength decreased by 3.5% after HIP, and improved the ductile property, the elongation increased to 15.8%.