Abstract: The prepreg tapes based on PA66 and carbon fiber (CF) were prepared by a melt-impregnation method, and the effect of CF content on their tensile properties and crystallization-melt behaviors were investigated by using universal material testing machine, diffractometer, differential scanning calorimeter, scanning electron microscope, dynamic thermomechanical analyzer and thermogravimetric analyzer. The results indicated that the introduction of CF led to a change in crystalline structure of α-form, which promoted the heterogeneous nucleation of PA66 and improved the crystallization temperature accordingly. The bimodal melting behavior of PA66 became more significant in the presence of CF, and its higher melting temperature tended to increase first and then to decrease. This may be due to the nucleation effect of CF, which induced and promoted the crystallization of PA66. Moreover, a grain refinement phenomenon was observed due to the huge amounts of crystal nucleus, thus resulting in a decrease of melting temperature. The increase of CF content could make nucleation saturated, which increased the number of nucleus and improved the melting temperature accordingly. The tensile strength, storage modulus and loss modulus of the prepreg tapes were improved with an increase of CF content.