For the purpose of standardization and practicability of natural dyeing, the mordanting and dyeing properties of Acorn Shell was studied. Appropriate extraction, dyeing and mordanting condition of Acorn Shell were determined, and the effect of mordanting method on dye uptake and color fastness of dyed fabric was investigated. The maximum absorbance of Acorn Shell solution was at 287.5nm and 294nm. The pH effect was stable in the color difference changes. The optimum temperature to extract Acorn Shell was during 1 hour in $60^{circ}C$. The effective dyeing temperature and time of silk were $80{sim}100^{circ}C$, 1hour. The silk fabrics dyed with Acorn Shell appeared yellow-brown. K/S value of dyeing fabrics was increased by mordant treatment. K/S value of post-mordanting was higher than pre-mordanting. Mordanting treatment attected color change of the dyed silk. In the case of Acorn Shell light fastness of appeared more than 3-5grades by post-mordanting. Abrasion fastness of appeared more than 3-5grades. Perspiration fastness of appered more than $3{sim}5grades$ by mordant treatment but Cu mordant treatment was $2-5{sim}4grades$. Dry-cleaning Fastness appered more than 4 grades except Cu mordant treatment. These fastness improvement were generally effective for mordant treatment, specially Al, Sn, Cr.