YBa₂Cu₃O_6+x(Y123)-Ag high-T _c superconducting wires were fabricated by plastic extrusion technique using pyrophoric synthetic and mechanical mixing powder with and without Ag addition(20 wt.%). This method involves powder preparation, plastic paste making, die extrusion, binder burn-out and the sintering process. In order to fabricate a good-quality superconducting body, it is required to use homogeneous and fine-size power as a starting materials. Y₂O₃-BaCO₃-CuO precursor powders with/without Ag addition were prepared both by pyrophoric synthetic(PS) and mechanical mixing(MM) method of raw powders. The formation kinetics of the powder mixtures into Y123 phase was investigated at various temperatures and times in air atmosphere. The powder prepared by PS method was more easily converted into a Y123 phase than the MM powder. The fine size and good chemical homogeneity of the powder prepared by PS method is attributable to the fast formation into a Y123 phase. The critical current density(J_c) of the Y123-Ag superconducting wires made by plastic extrusion method were in the range of 150 A/㎠∼230 A/㎠. depending on the charateristics of starting material powders. J_c of the wire prepared by pyrophoric synthetic powder with 20 wt.% Ag addition was 230 A/㎠.