The post-grouting process of bored piles has been widely used in China because it can improve the bearing capacity and reduce deformation. However， due to the large concealment of post-grouting construction， problems have occurred in many engineering applications. A large number of practices show that the bearing capacity of a single bored pile under the same condition often shows quite differences. Simply calculation according to the pile foundation specification will make the calculated value significantly higher than the static load test results， which brings great safety hazards to the construction project. The comprehensive estimation method proposed in this paper analyzed from several aspects， bringing in the increase amplitude of bearing capacity γ， the bearing capacity enhancement coefficient β， and the cmprehensive impact factor λ， covering the influence of various factors. The calculation formula is simple and easy to understand and the method is convenient and feasible. Moreover， the results are close to the actual after the application verification with high safety reliability， and good application effect.