Prof. Xin Xu’s group is the only domestic research group devoted to the development of density functional theory in China. Our group has proposed a series of innovational functionals and applied them to some important systems in chemistry. Specifically, our group first proposed the X3LYP functional that contains the form for the exact exchange energy density for a density that decays with Gaussian-type behavior at the long-range. X3LYP can precisely describe the hydrogen bonding systems and has been implemented in Gaussian03/09/16, Jaguar, ADF, Crystal, Orca, etc. popular quantum chemical codes. X3LYP functional has also been introduced in many academic monographs and textbooks, including the domestically famous “Quantum Chemistry” written by Prof. Guang-Xian Xu and Le-Min Li. Our group further developed a series double-hybrid XYG3-type functional that is based on the adiabatic connection formalism and the Görling–Levy coupling-constant perturbation expansion to the second order. The XYG3-type functional includes XYG3, XYGJ-OS, xDH, etc., which are one of the fastest and the most accurate double-hybrid functionals in the world. Utilizing XYG3-type functional, our group has comprehensively investigated the chemical reaction processes and interaction mechanisms of energy, environment, biology, and material science.