A method to predict the tensile strength of needle-punched carbon/carbon composites is elaborated in this paper. Based on the geometric characters gained by using optical microscope, the structures of the material can be classified as five typical unit cells, which can reflect the mutual alignment relationship of planar fiber tows and needle fiber tows. With the elliptical inclusion theory and Puck’s strength criterion, the stress–strain curves and progressive damages of these five unit cells are obtained. Based on these results, the mechanical behavior of needle-punched carbon/carbon composites under tensile loading can be predicted. It is found that the predictions of the composite under unidirectional tensile loading agree well with the experimental data.