Abstract: Due to the anisotropic characteristics of C/C composite pins, the loading direction effects on the shear strength and shear constitutive model based on the Weibull model were studied. Then the Weibull model was invited to analyze the statistic distribution of the shear strength, and the parameters were estimated by the least square method. Based on the failure mechanism of C/C composites, an elastic-damage constitutive model with Weibull distribution was proposed, and the parameters were estimated with experimental data. The results show that the two-parameter Weibull function can be used to characterize the statistic distribution of shear strength according to the Kolmogorov-Smirnov test, and the C/C composite pins show the highest shear strength along the 45° direction. The shear stiffness of C/C composite pins decreases with the increasing shear angle, which decreases from 19.46 kN/mm (0° direction) to 12.70 kN/mm (90° direction).