Amur cork tree contains yellow natural basic dye largely used for dyeing on silk. Dyeabilities and fastnesses of the colorant on silk fabrics were investigated , According to dye concentration, pH, temperature, time of pre- and post- treatment of mordant, K/S values and fastnesses of the silk fabrics were examined. As a results, K/S values of dyed silk fabrics were increased by pre- and post-treatment with chinese gallotannin. The optimum rendition of chinese gallotannin pre-treatment was 0.15% concentration, pH 4, $70^circ{C}$, and 45min, and that of post-treatment was 0.05% concentration,$60^circ{C}$, and 30min. The wash fastness and the light fastness were enhanced to 4 grades and 2~3 grades.