In this study, for improving the shear and flexural strength of PHC pile, 1) filled concrete for section reinforcement, 2) composite behavior of pile body and filled concrete and ring type composite shear connector for shear reinforcement and shear reinforcement for reinforcement of shear strength, 3) for flexural reinforcement with internal reinforcing rebar, 4) and head reinforcement rebar, mechanical properties of CFP pile by reinforcement stage were analyzed. Through FEM analysis, the effect on the shear strength and flexural strength of CFP pile according to the layout spacing and flexural reinforcement of ring type composite shear connector was investigated. In addition, based on the limit state design method, the CFP pile shear and flexural design were conducted and the horizontal shear, shear and flexural structural tests were performed on the basis of the CFP pile design method. These results were compared and analyzed to verify the structural performance of CFP pile and its validity in the application of the limit state design method. 1. According to the application of internal reinforced flexural rebar (D13-8ea) through finite element analysis, the flexural and shear strengths increased 94.8kN(31.7%) and 54.9kN(14.0%) respectively. However, the application of head reinforcement rebar(D19-8ea) was presented with an additional 142.9kN(40.8%) flexural strength, but no shear strength was increased. 2. Through push out test, the horizontal shear strength of CFP pile body and filled concrete was measured by interfacing. Moreover, the horizontal shear strength of the CFP pile was calculated and compared to the experimental value, showing a deviation of 2.2% and -2.3%, indicating proper shape and spacing of ring type composite shear connectors(600mm). 3. The theoretical values of the KS standard and the Japanese PC pile translation "Design and Construction of PC pile" and the limited state design method were calculated and compared with the experimental values. The average deviation of the experimental value/theoretical value() is 13.9% and the average deviation of the experimental value/theoretical value() is 6.8%, which is considered to be a more stable evaluation method. 4. As a result of conducting a flexural test, the mean deviation of Mu,exp/Mu,ks, Mu,exp/Mu,sh, was 65.6% and 69.2%, respectively, and the deviation increased with the increase of the rebar ratio. The average deviation of Mu,exp/Mu,Mu,LSD was 7.7%, indicating a more stable theoretical value. The regulations for the reinforcement ratio of PHC pile are 0.4% or higher(KS F 4306), and the patterns of brittle failure are shown without reinforcement, assuming that the crack generation is destructive, and the linear elasticity theory(σP/A±M/Z) is designed However, the reinforcement ratio of the CFP pile test specimen was 1.2% to 2.7%, similar to the ductile reinforced concrete behavior. 5. The maximum shear strength and maximum ultimate bending moment shown in the CFP pile test specimen performed in this study were greater than the PHC pile D900(630.8kN) and D700 (397.3kN·m) KS standards, respectively. Therefore, it is deemed possible to apply the limit state design method to structures that were difficult to apply with the PHC pile through the shear reinforcement spacing and flexural reinforcement design, and to design the CFP pile in a reasonable.