Objective: To study the mechanical degradation characteristic of carbon fiber reinforced polyester(CFR/PE), polysulfone (CFR/PSF) and polyetheretherketone (CFR/PEEK) in. physiologicalenvironment. Methods : Compressive strength and modulus of three samples were tested fbllowingconditioning in physiological saline at 37℃, 65℃ and 95℃ for time periods from 0 to 256 days. Drysamples were used as controls. The percentage value of degradation of compressive strength andmodulus of each of the materials were calculated and compared. Results :No significant loss incompressive strength and modulus values of CFR/PEEK of the saline-saturated or dry controlsamples as a function of conditioning time or temperature. However, the compressive strength andmodulus of CFR/PE and CFR/PSF were significantly decreased as long as saline saturate. Thecompressive property value of CFR/PE and CFR/PSF are corelative to both time and temperature.Conclusionf There is satisfactory biomechanical stability of CFR/PEEK in physiologicalenvironment. It must be taken into consideration of materials' mechanical degradation propertieswhen CFR/PE and CFR/PSF be used in vivo as implants.