Abstract: In pile foundation engineering, the length of end bearing pile is determined by the depth of bearing layer. In order to make the work of material preparation and program scheduling, etc., more accurately, the acquisition of this depth has become a major focus in pile foundation projects.. In traditional way, geological prospecting column chart combined with planar graph is generally used to estimate through complicated manpower calculation. With the development of BIM technology, a large number of BIM based prediction methods have emerged in recent years. In this context, this paper proposes a method about predicting the pile length in quantity. Compared with the existing methods, it is more efficient and needs less manual operation, and its accuracy has been verified in practice.