Abstract: The tensile stiffness of unidirectional and multi-directional hybrid fiber composites was studied. The influence of hybrid ratio and dispersion degree on hybrid effect was considered on basis of hybrid law and the prediction formula of the tensile modulus of unidirectional hybrid fiber composites was proposed. Tensile modulus of multi-directional hybrid fiber composites was obtained by experiment and estimated with the classical laminate theory. Based on the effects that hybrid ratio and dispersion degree have on the tensile modulus, the estimation formula of tensile modulus of multi-directional hybrid fiber composites was corrected. The result shows that the tensile modulus of hybrid fiber composites relates to the hybrid ratio and dispersion degree, the increase of dispersion degree can improve the longitudinal tensile modulus of unidirectional hybrid fiber composites to some extent. The tensile modulus dotained by classical laminate theory has an error compared with the experiment value, while by using the proposed formula, the tensile modulus of hybrid fiber composites can be estimated more exactly.