Abstract: The feasibility of using probabilistic energy method to evaluate the ultimate load capacity of cast-in-situ pile has been investigated with the data derived from the results of CAPWAP hack-analytic and static pile load test of 200 pile cases in the urban district of Nanjing city. The dynamic soil-pile interaction model, similar to that used in the CAPWAP method, is adopted in this method. The energies delivered and transformed during the high strain dynamic tests is comprehensively analyzed, and the formulas calculating pile capacity are derived based on the principle of energy balance. The model parameters, including the shaft dam ping factor Js, the tip damping factor Jt, shaft quake Qs, and tip quake Qt are treated as random variables with mean values, standard deviations and probability distribution functions determined by a statistical analysis. The statistics of regional experiments, such as the means and standard deviations of the model parameters, are used as given values in the calculation of pile capacity. The other required values, including the energy delivered to the pile head during each hammer blow, the pile penetration of each blow, the maximum velocity at the pile head, and the pile dimensions and elastic properties, are easi1y measured. The distribution of pile capacity is determined through a Monte Carlo simulation. Furthermore, the authors proposed here a formula to calculate the probability of the evaluated pile capacity exceeding certain design load. The rationality and accuracy of this method are demonstrated in a comparison of the pile capacity calculated with this method and the results of static pile1oad test.