Abstract: In this work, the composites consisting of continuous PAN-based carbon fibers and vinyl ester resins were fabricated by pultrusion processing, in which on-line surface treatment on the carbon fibers by thermal oxidization was carried out. The microstructures of the surfaces of both treated and untreated carbon fibers and the fracture morphologies of the composites were analyzed by using SEM. Also, the quasi-static mechanical properties and the thermodynamic mechanical properties of the composites were measured with Universal Materials Tester and Dynamic Mechanical Thermal Analyzer (DMTA), respectively. The results show that the surface roughness of the carbon fibers increases by the surface treatment, and thus the interfacial adhesion between the carbon fibers and the vinyl ester resins rises, and the mechanical properties, especially the Interlaminar Shear Strength (ILSS), of the composites are obviously improved. Moreover, according to the thermodynamic mechanical properties of the composites, it is found that the improvement of interface properties causes the loss modulus reduced, and can increase the fatigue resistance of the composites.