The invention discloses a high-fastness suit fabric dyeing process and relates to pure wool fabrics. The high-fastness suit fabric dyeing process comprises the following steps of S1, pretreatment, S2,dyeing including heating reactive dye solution to 76-82 DEG C and holding the temperature for 50-60 min, then adding in ammonium hydroxide to regulate the PH to 8-9 for treatment for 10-20 min, thencooling down to 50-60 DEG C, adjusting the PH to 4.5-5 for treatment for 8-10 min, and sequentially performing cold water washing, soaping, cold water washing and drying, wherein the active dye solution is composed of, on weight the fabric, 2-3% of reactive dyes, 2-3% of acetic acid, 1-2% of low-temperature additives, 2-3% of ammonium sulfate and 0.1-0.2% of gadolinium chloride, S3, fixation including immersing the dyed fabric into dye-fixing solution at 40-60 DEG C for treatment for 12-25 min, wherein the dye-fixing solution is composed of, on weight the fabric, 2-4% of dye-fixing agent, andS4, cleaning. During the dyeing process, gadolinium ions can be complexed with amino and carboxyl of wool fiber as well carboxyl and amino of dye macromolecules to improve the dye uptake as well as the wool dyeing fastness and the mechanical performance.