Abstract: A method was proposed to improve the bearing capacity and ductility of CFRP PVC (Carbon Fibre Reinforced Plastics- Polyvinyl Chloride) reinforced concrete columns using H-shaped steel. Ten cylindrical specimens were designed with varying parameters of hoop coefficient and section steel content. The failure process and mechanical properties of the composite column under axial compression were studied, and the constraint mechanism of the composite column was analyzed. The results indicate that the presence of steel sections causes ductile failure with warning signs in the specimens, and creates composite constraints with CFRP PVC pipes. The constraint efficiency is higher than previous related studies, and it is recommended that the confinement coefficient of CFRP PVC pipes be greater than 0.41; When the same hoop coefficient is used, as the steel content increases, the confinement efficiency of the specimen gradually decreases, but the ductility shows an upward trend; When subjected to weak constraints, an increase in steel content will lead to a degradation of axial compression stiffness. Conversely, when subjected to strong constraints, the critical hoop coefficient is between 0.4 and 0.68; Finally, based on the experimental results, a composite constraint model and axial compression bearing capacity calculation method were established, with an error of less than 5% in the calculation results and ensuring safety.