The source of data used in the process of building geological section is drillhole data, and the way of modeling deals with the problem of depositional termination or section smoothing is more complex, stability and robustness is not satisfactory. So it is difficult to apply to the actual production process. To solve this problem, this article proposes a geological section construction algorithm based on virtual drilling controlling. First of all, according to processing strategy of depositional termination we build the virtual drilling on the thinning out treatment; second, in accordance with segments smooth strategy, we use four-point interpolation subdivision algorithm to build subdivision smoothing virtual drilling; third, we rebuild the polygon topology on formation line feature, that can build strata polygon entity; and the last, we integrate various of geological section's mapping elements to finish the output. The example shows that using the algorithm proposed in this paper to build the geological section can accurately reflect the geological structure of the study area, and increased segmentation times can significantly improve the plots moothing effect. This algorithm puts the virtual drilling into all aspects of geological section building and takes it as the middle unit in the algorithm. It can effectively simplify the implementation process, and ensure the stability and efficiency of the algorithm.