This paper surveys the extraction condition of polygenetic natural dye, Sappan Wood and the effect of ash to the dyeability and fastness. The appropriate time for extracting Sappon Wood was 1hour. The pH was increased as the amount of ash increase. The pH was nearly invariable according to the time of ash solution, the extracting times and temperature. Absorbance of dyeing fabrics was about 480nm. From the result of K/S value determination of fabrics, 10g/$ell$ quantity of ash was surfficient for treatment and the amount of Sappon Wood was in 100% o.w.f.. K/S value of fabrics pre-mordanted or post-mordanted were higher than that of fabrics simultaneous mordanted.K/S value was increased as pH of mordanting bath decrease and pre-mordanting and post-mordanting fabrics increased the amount of absorption (K/S value) compared with non-mordanted fabrics. It was found that pH of mordanting bath affected the amount of absorption and color change of dyed fabrics. Light fastness of fabric dyed was very poor and the fastness of fabric dyed was not influenced by the mordanting conditions and methods.