In the graphene family, bilayer graphene (BLG) exhibits more diverse electronic structures and higher tunability than monolayer graphene due to its unique interlayer coupling effect. As a result, it has emerged as a crucial branch in functionalization research. By using its interlayer as an embedding channel, BLG avoids impairing graphene's intrinsic conductivity, a common issue with surface modification. Furthermore, the interlayer coupling enables the synergistic engineering of its electronic structure, resulting in performance superior to that of monolayer graphene. Therefore, the interface of BLG represents a potential functionalization site. Based on the aforementioned research status and issues, all calculations in this study are performed using density functional theory (DFT) through the Vienna ab-initio Simulation Package (VASP). In order to accurately describe the van der Waals (vdW) interactions (π-π stacking) between the layers of AB-stacked BLG, the DFT-D3 method is employed for vdW correction to investigate the influence of functional groups on BLG electrical properties. This study focuses on four functional groups (—OH, —CO, —CHO, and —COOH), in which O and H atoms can readily form chemical bonds with the carbon atoms in BLG. Through interlayer modification, the interactions between these functional groups and the carbon atoms are analyzed to realize the regulation of interlayer coupling and electronic structure characteristics of BLG. Inserting —OH and —CHO into the interlayer of BLG results in higher stability and lower interfacial binding energy, whereas inserting —CO and —COOH leads to reduced stability. The Fermi level of BLG shifts to varying degrees when functional groups are inserted. Specifically, the insertion of —OH or —COOH causes the Fermi level to shift toward lower energy levels, reducing the highest occupied energy level. In contrast, the insertion of —CO or —CHO shifts the Fermi level towards higher energy levels, exciting more electrons to higher energy states and causing electron filling at elevated energy levels. The band structure of BLG undergoes significant modifications due to the insertion of functional groups. The original parabolic band dispersion is disrupted, and the band distribution becomes more complex, with line trajectories and crossing characteristics changed. The calculations of partial density of states (PDOS) and charge density difference reveal orbital hybridization and charge transfer between the functional groups and BLG. All four functional groups form covalent bonds with the carbon atoms of BLG, exhibiting characteristics of chemical adsorption. Moreover, the extent of charge transfer and the perturbation of charge density vary significantly among the different functional groups. This study aims to clarify the regulatory mechanisms and underlying principles of functional groups, providing a theoretical basis for designing BLG-based electronic materials with specific functionalities, while also enriching the research framework of interlayer functionalization in two-dimensional layered materials.