Exhaustion increase using cationic dyes on polyamide fibers are not easy work due to the limited amounts of the functional end groups(-COOH) in the substrates. Therefore, to enhance dye exhaustion, polyamide fibers are required to be modified onto desired surface properties of the fibers using anionic bridging agent. In this study, synthetic tanning agent for pre-treatment finishing and cationic dye(berberine chloride) for dyeing of polyamide fibers were used. For surface modification, polyamide fibers were pre-treated with synthetic tanning agent at various concentrations and temperatures. The increased concentration and temperatures of synthetic tanning agents had resulted in exhaustion increase. The modified polyamide substrates skewed increased cationic dyeing exhaustions and the corresponding dyeing results from treated samples represented higher exhaustion properties than those of non-treated counterpart. The increased dyeing effects of cationic dye can be attributed to the supplied ionic interaction and electrostatic attraction sites on the surface of polyamide substrates.