For the purpose of standardization and practicability of natural dyeing, the mordanting and dyeing properties of Puerariae Radix was studied. Appropriate extraction, dyeing and mordanting condition of Puerariae Radix were determined, and the effect of mordanting method on dye uptake and color fastness of dyed fabric was investigated. The maximum absorbance of Puerariae Radix solution was at 290nm and 301nm. The pH effect was stable in the color difference changes. The optimum temperature to extract Puerariae Radix was during 1 hour in loot. The effective dyeing temperature and time of silk were 80$~$ 100$^{circ}C$, 1hour. The silk fabrics dyed with Puerariae Radix appeared yellow-brown. US value of dyeing fabrics was increased by Fe, and Cu mordant treatment. Mordanting treatment method affected color change of the dyed silk. In the case of Puerariae Radix light fastness of appeared more than 2-5 grades by mordant treatment. Perspiration fastness of appered more than 4 grades by Al, Sn, Cr mordant treatment. Fastness of abrasion and dry-cleaning appered more than 4-5 grades. These fastness improvement were generally effective for mordant treatment, specially Al, Sn, Cr.