The textile fabric have the functions of sanitation, decoration, wearing style and washing in the practical use. Among various texitle fiber, silk has less utilities than synthetic fiber in practical use although silk has good benefits of the high quality. Thus no textile fiber, neither natural nor synthetic, has all the functions. In this sence, many blend yarns have been improved various functions of fabric. However, this has been disturbed with the problem of dyeing, especially in the case of blend fabric of silk. In this study, we dyed silk/PET blend fabric in one step useing one bath dyeing method by acid dyes/disperse dyes. The results of the experiments can be summarized as follows; 1) Yellow index of silk fabric treated at $130^{circ}C$ increased about 7.8 (color difference 4.5 NBS) and whiteness decrease about 5%. 2) Both elongation and tensile strength of silk fabric treated at $130^{circ}C$ of pH 5-6 decreased about 10% and tensile strength of silk spun yarn treated at $60^{circ}C$ of pH 10 have little changed. 3) While silk/PET blend frbric dyeing, silk soiling of disperse dyes causes from difference of dyeing rate and degree of silk soiling with dyes. 4) Fastness and soiling of silk/PET blend fabric dyed by one bath dyeing method of acid dyes/disperse dyes was same as two bath dyeing method.