The buoyancy of groundwater in clay layers is a critical factor that influences the behavior of geotechnical engineering structures. However, there is still a lack of understanding regarding the factors that contribute to the reduction of groundwater buoyancy. This study aims to elucidate the influence of soil parameters and matric suction on groundwater buoyancy, employing laboratory model tests and innovative experimental methods. The research findings uncover noteworthy variations in the reduction coefficient of groundwater buoyancy contingent upon the clay type, ranging from 0.45 to 0.85. Furthermore, experimental results indicate that matrix suction effectively diminishes pore water pressure but exerts minimal influence on groundwater buoyancy. It is elucidated that pore ratio, permeability coefficient, and water content evince a robust positive correlation with the buoyancy reduction coefficient, whereas dry density and wet density exhibit an inverse trend. Conversely, parameters such as cohesion, saturation, internal friction angle, specific gravity, liquid limit, and plastic limit manifest minimal correlation with the buoyancy reduction coefficient. These findings have practical implications for anti -floating design in geotechnical engineering.