A method for predicting elastic constants of 3-D braided ceramic matrix composites was established by means of pore elements and taking into account its random distribution. The porosity was measured by industrial computed tomography (CT) scan systems. The Monte-Carlo technique was utilized to simulate the stochastic distribution of the pores in the 3-D braided ceramic matrix of the unit cell model. The effect laws of porosity on elastic constants of 3-D braided ceramic matrix composites were obtained through the finite element model of the unit cell. The results indicate that: (1) there exists obvious influence of porosity on the elastic constants of 3-D braided ceramic matrix composites; (2) for a certain porosity

the location distribution of pores has almost no effect on the elastic modulus along fiber bundle orientation; (3) the elastic modulus along fiber bundle orientation decreases with the increasing porosity. The tension test of SiC/SiC composites was also conducted at ambient temperature. The predicted value of elastic modulus matches with the measured data. The result has validated the proposed methodology for predicting the elastic constants of 3-D braided ceramic matrix composites with pores.