Abstract: To investigate the influence of dry-heat treatment on the structure and properties of AN(acrylonitrile)-g-Casein fibers,the scanning electron microscope,fourier transform infrared spectroscopy,and X-ray diffraction were used.The results indicated that the dry-heat treatment below 140℃had slight influence on the yarn shrinkage and whiteness and improved its strength.When temperature of the dry-heat treatment exceeded 140℃,the fibers exhibited distortion of the fiber,increase in yellowing and decrease in crystallinity.140℃was found to be the critical temperature of AN--gCasein fibers for dry-heat treatment.