Constructing a high-quality potential energy surface (PES) is fundamentally important for many spectroscopic calculations and quantum dynamics simulations. A small deviation of PES may cause unexpected errors, leading to quantitatively or even qualitatively incorrect results. For those ab initio PESs fitted from single-point energies (SPEs), their accuracies depend on the electronic structure methods used for SPE calculation, the number of and the distribution of fitting points, and the PES models as well as the parameter optimization procedures. High-level electronic structure methods can provide faithful ab initio points, but they are extremely expensive for high-dimension systems. People have to find a balance between the accuracy and computational cost of ab initio points. Methods that could reduce the point number are thus meaningful, as they allow us to use higher-level methods in given computational resources.