Based on the experimental values of the RPC beams prestressed with CFRP tendons of different parameters, the ductility and deformability of these beams were studied, and a corresponding parametric study of the ductility was conducted on the basis of the numerical analysis program. The research shows that the RPC beams are of better deformation capacity than normal concrete beams, and the proposed unloading rigidity formula can be used to calculate the actual unloading curve. It can be concluded from the parametric study that the deformability and ductility of the RPC beam prestressed with CFRP tendons can be enhanced by increasing the ultimate compressive strain of the concrete, the unbonded length of the tendon, the percentage of the compressive reinforcement and the partial prestress ratio, and by decreasing the effective prestress in tendons.