The invention provides a special Ti-6Al-3V welding wire for Ti-6Al-4V ELI titanium alloy and a machining process of the special Ti-6Al-3V welding wire. The special Ti-6Al-3V welding wire includes the alloy components of, by weight, 5.5-6.75% of Al, 2.5-4.5% of V, smaller than 0.20% of Fe, smaller than 0.13% of O and the balance Ti. The machining process of the special Ti-6Al-3V welding wire includes the following steps that a, the raw material weight ratio of Al-V intermediate alloy to pure metal aluminum to titanium sponge is calculated according to the design components of the welding wire, and the raw materials are smelted into ingots through vacuum arc remelting; b, the ingots are forged into bar billets; c, the bar billets are rolled into bars; d, the bars are rolled into wire billets; e, the wire billets are stretched; f, the wire billets are straightened, descaled, polished and ground; g, the wire billets are thermally treated and then stretched into wires; h, vacuum annealing is conducted on the wires after alkaline washing and acid washing are conducted on the wires; i, the wires are straightened and then cut into straight wires; j, the straight wires are ground into finished products. Through the adjustment of the content of main alloy elements and impurity elements and the reasonable production process, the titanium welding wire with better mechanical performance matching performance with the Ti-6Al-4V ELI titanium alloy is produced, and the performance of a weld joint of the welding wire can meet the index requirements of a manned cabin.