The TA15 titanium alloy plates were prepared by laser deposition manufacturing using TA15 titanium alloy powder. The effect of annealing treatment and deposition direction on microstructure, and mechanical properties of laser deposition manufacturing TA15 titanium alloy and alpha phase deformation mechanism has been studied. The experimental results showed that the length-width ratio of alpha phase in microstructure shows risen when increasing the annealing temperature; the mechanical properties are different in deposition direction and vertical deposition direction; the tensile strength in the deposition direction is obviously lower than that in the vertical direction; columnar crystal grain boundary has a baffling effect on alpha lamellar distortion; alpha lamellar deformation or fracture by extrusion and slippage; different directions have different tensile fracture modes, deposition direction is ductile fracture, vertical deposition direction is semi-cleavage and semi-ductile fracture.