Abstract: Pile foundation design approach is an important factor for determining the bearing capacity of foundation piles. The differences between pile foundation design approaches have significant influence on reliability analysis of piles. Seven design approaches for pile foundation are collected for this study, which are widely used at home and abroad. Subsequently, based on the CPT design approach and bearing capacities of piles determined by seven pile foundation design approaches, the bias factor of design approach is defined, and the calculation formula for reliability index of foundation piles considering various design approaches are presented. The results from case study indicate that, the degree to which pile foundation design approaches affect reliability level of pile bearing capacity greatly varies with pile foundation design approaches. However, it is shown the stable impact of pile foundation design approaches on reliability analysis of piles, which supports the proper adoption of pile foundation design approach in practice. Due to that reliability indices based on different pile foundation design approaches are small and have large differences, the reliability indices obtained can be accepted to evaluate the level of safety for pile foundation design approach, but cannot be directly accepted as the criterion to judge pile reliability.