Taking a project in Dongying as an example, based on the test results of pile test in the Yellow River flood alluvial formation, the relation curve between the measured average value of the ultimate bearing capacity of single pile and the height of the pile bottom (which can be converted into pile length) under the condition of the same pile top elevation (-5.7m) is set up. The difference between the test pile test and the measured value of the ultimate bearing capacity of the single pile is quite different from the predicted value. The reasons and the optimal design method of pile foundation bearing capacity are introduced. According to the test results of the pile foundation, the measured value of the ultimate bearing capacity of the single pile under the same length and diameter of the pile is about 10% compared with the predicted bearing capacity, which can achieve the potential of excavating the geological conditions, reducing the number of piles and saving the cost of the project. Relevant test methods and methods of optimizing pile bearing capacity design can provide reference for engineering design under similar geological conditions and the establishment of regional pile bearing capacity database.