This article establishes a numerical analysis method based on incremental deformation, which is applicable to both bonded partially prestressed concrete beams and unbonded partially prestressed concrete beams throughout the entire process of loading. The method proposed in this article can simulate the performance of components in the descending section after reaching their peak bearing capacity, and can consider the changes in material stress-strain relationships caused by the unloading of non prestressed steel bars and concrete due to the structure entering the descending section of bearing capacity. Using the method established in this article, the effects of different loading methods, span to height ratio, comprehensive reinforcement index (CRI), partial prestressing ratio, and concrete compressive strength on the ductility performance of unbonded partially prestressed concrete beams were studied. Research has shown that the curvature ductility coefficient of unbonded partially prestressed concrete beams decreases with the increase of the comprehensive reinforcement index (CRI). For a given comprehensive reinforcement index (CRI), the difference in curvature ductility coefficients between bonded and unbonded prestressed concrete beams was compared and analyzed. Analysis shows that when the comprehensive reinforcement index (CRI) is between 0.15 and 0.20, the curvature ductility coefficient of unbonded prestressed concrete beams is close to that of corresponding bonded prestressed concrete beams; When the comprehensive reinforcement index (CRI) is greater than 0.20, the curvature ductility coefficient of unbonded prestressed concrete beams is greater than the corresponding curvature ductility coefficient of bonded prestressed concrete beams; When the comprehensive reinforcement index (CRI) is less than 0.15, the curvature ductility coefficient of unbonded prestressed concrete beams is smaller than the corresponding curvature ductility coefficient of bonded prestressed concrete beams