In the Previous studies, we reported about the synthesis of poly(3-methylence-3-methylenesodiumbisulfite-bis(4-hydroxypheny )sulfone] (PMSBPS ) and their effect on the staining of direct dye on nylon in the dyeing of nylon/cotton union. The results shoved that PMSBPS have good staining resist effect on nylon in the dyeing of nylon/cotton union. In this study, the staining resist effects of PMSBPS in varied dyeing process and method were investigated, and the fastness to washing, light, and rubbing of the deed N/C unions was tested. The results are as follows , 1. In the two bath two step method, the staining of direct dye on nylon was decreased with the concentration of PMSBPS, and the fastness to washing, light, and rubbing of the dyed N/C unions were increased by addition of PMSBPS. 2. In the one bath two step method, optimun concentration of PMSBPS was 4% 0.w.f..