Compared to the Bin Jiang group's works, our sampling procedure has the following modifications. Firstly, the initial points are randomly selected and do not rely on the minimum energy path (MEP). Secondly, the seed points for active learning are also generated via random methods instead of using points near the old training points with a small random displacement. These two differences make it easier to quickly sample a large amount of region, which is important for the IPES of VdW complexes. Another modification is to use a two-step sampling procedure to increase the speed of total point sampling, where the sampled point set of the first single-precision AL would be the initial set of the second doubleprecision sampling. The result of our calculation (see) shows that the single-precision AL could produce a good initial set and the next double-precision AL needs only several steps to achieve low uncertainty.