In this paper, the hybrid effect on the flexural behavior of pitch/PAN hybrid unidirectional CFRP was theoretically and experimentally studied according to laminate constitution. First, the stress-strain curves of pitch based unidirectional CFRP (XN40/25CH) and PAN based unidirectional CFRP (T300/25CL) were examined. These stress-strain curves were obtained by tension and 4-point bending tests. Secondly, the hybrid effect of the flexural behavior predicted by the laminate beam theory was confirmed by the experiments.The results are as follows.(1) Both slopes of the stress-strain curves of XN40/25CH and T300/25CL become steeper as the tensile strain increases. They become gradual as the compressive strain increases, and the compressive stresses approach a constant value. So, these CFRP's stress-strain curves indicate non-linear behavior. The constant value of compressive stress for XN40/25CL is nearly half of T300/25CH.(2) The hybrid CFRP of XN40/25CH laminated with T300/25CL on the compressive side shows a little decrease in elastic modulus and large increase in flexural strength compared with the original XN40/25CH. This is a hybrid effect on the flexural behavior.