Abstract: The uniaxial tensile stress-strain behavior of unidirectional fiber reinforced ceramic matrix composites was studied using a micromechanical approach. The Budiansky-Hutchinson-Evans (BHE) shear lag model was used to analyze the micro stress field of the damaged composites. The critical matrix strain energy criterion，strain energy release rate criterion and Curtin's statistical failure criterion were used to describe the matrix cracking，interface debonding and fiber failure，and to determine the matrix cracking space，the interface debonding length and the percentage of the fracture fibers. By combining the shear lag model and three damage models，the stress-strain curve of each damage stage was modeled，and the exact model of predicting the toughness and the strength of the composites was established. The influences of the interface parameter and fiber Weibull modulus on the damage of the composite and the stress-strain curve were discussed. The uniaxial tensile experimental data of ceramic matrix composites at room temperature was compared with the present analysis. The stress-strain curve of each damage stage，the failure strength and strain agreed well with the experimental data.