Aiming at the technical problems of low surface precision and difficulty to control the microstructure and properties of titanium alloys formed by plasma arc 3D printing, the influence of process parameters on the size and shape parameters of the deposited metal was studied through the control variable method, and the most suitable deposition process parameters were obtained by optimization. The Ti-6Al-4V component can be divided into three regions, the top region is mainly composed of coarsen αGB and αM, and the middle layer region includes a small amount of lamellar structure (α colony) and αM, the size of which decreased significantly, and the bottom area was mainly composed of relatively uniform basket-like α＋β; The dimensional error of the titanium alloy components obtained by plasma arc 3D printing does not exceed 2%, and the tensile strength is 1 150 MPa. The forming accuracy and mechanical properties of the components meet the requirements for use.