Abstract: In Chinese available codes on foundation pile testing (both dynamically and statically), the number of tested piles is to be determined by a rate of the number of total piles. But when the number of total piles is extremely large, limited by time or cost, the available codes on foundation piles testing can not be carried out, especially for piles testing statically. On the other hand, the spirit of probability and statistics in available criterions, which determines the number of tested piles with a rate of the number of total piles, is vague. Upon the two problems above, the probability model for estimating the results of pile testing is deduced, with which the probability meaning of available codes on foundation piles testing is studied and the factors that affects the results of pile testing is analyzed. And the method of evaluating the quality of foundation piles with statistics is introduced. In the end, combined with engineering, some solutions to the problems are probed into.