Abstract: The traditional pile length design is calculated based on the geological prospecting report data, which is always massive and cumbersome, and can easily lead to data deviation. For the accuracy of data, a 3D geological model is established by using the BIM technology to simulate the distribution of soil and rock, and the pile foundation is also modeled based on the existing design conditions. Through the combination of the two models above, we realized the application of BIM-based 3D geological model in pile length checking.