Recently there has been a growing interest in the use of natural dyes in textile applications. Natural dyes can exhibit better biodegradability and generally have a higher compatibility with the environment. In this study, the colorants of Catalpa ovata bark were extracted with water and analyzed by spectrophotometry for their main colorant species. Cotton, silk and wool fabrics have been dyed with aqueous extract of Catalpa ovata bark and their dyeabilities on the fibers were studied. Additionally the fastness to washing, drycleaning and light, and the effects on bacteriostatic rate and UV-B protection rate were also investigated. The major colorant of the extract of Catalpa ovata bark was shown to be 6-O-trans-caffeoyl-$eta$-D-glucopyranoside. Cotton, silk and wool fabrics dyed with the extract of Catnip ovata bark were colored in yellowish red tint. The optimum dyeing condition of the colorants extracted from Catalp ovata bark was three repeated dyeing at $95^circ{C}$ for 1 hr using post mordanting. For dyed silk and wool fabric, the fastness to washing were improved by mordanting, and the fastness to drycleaning were very outstanding. In case of wool fabric dyed with the extract of Catalpa ovata bark, the bacteriostatic rate was increased drastically by 98.0%, and UV-B protection rate was increased by 97.3%.