Enamel,the hardest tissue in human body,has excellent anti wear properties.The hydroxyapatite crystals and organic matters strictly arrange in alternate within the enamel,and the microstructure of enamel is similar to that of fiber reinforced composites.Two models,original enamel and deproteinization enamel,were established using finite element analysis (FEA),and the effect of organic phase on mechanical properties of enamel was investigated.Results show that the enamel has anisotropic mechanical properties.As the angle between loading direction and the c axis of HAP crystals is increased,the compression modulus and yield stress of enamel are decreased,and the lowest values occur in off axis when the angle is 45°.The organic phase within enamel has a significant influence on its mechanical properties.With the organic phase within enamel being removed,the compression modulus,shear modulus and yield stress of enamel are decreased，but the compression yield stress almost remains constant.The results will extend the understanding of the relationship between the microstructure and chemical composition of enamel and its mechanical properties,and are helpful to the development of new dental restorative materials.