To maintain the integrity of internal floating roof tanks, curb environmental pollution and guarantee the safety of tank farms, it is important to determine the oil flow features that impact the floating roof during the oil receiving process, especially when the floating roof falls to the bottom of the tank. In this study, the finite volume, volume of fluid (VOF), and realizable k-ε turbulence models and the pressure implicit with splitting of operators (PISO) algorithm were adopted to establish a three-dimensional physical model of an internal floating roof tank and simulate the oil receiving process. A pressure test platform was then set up to validate the model's viability. The flow field characteristics and influencing properties of the impact of the liquid against the floating roof under different oil inlet velocities, initial liquid levels, medium densities, and tank diameters were analyzed and compared. The results showed that increasing the oil inlet velocity and medium density led to the maximum pressure and the impact force at different moments of the liquid against the floating roof also increasing. An increase in the oil inlet velocity, led to greater turbulence on the opposite the inlet, and higher pressure at the edge of the floating roof in the upper area opposite the inlet. At an oil inlet velocity of 4.0 m/s, the maximum pressure was 135.5 kPa and the maximum impact force peak was 13.967 MN. The initial liquid level increase had little influence on the liquid's impact on the floating roof, and the high pressure zone was at the edge of the floating roof opposite the inlet. When the initial level was 0.5 m, the maximum pressure was 135.81 kPa and the maximum impact force peak was 14.021 MN. As the density of the medium increased, the greater the turbulence on the inlet relative side and the higher pressure at the edge of the floating roof in the upper area of the inlet relative side. When diesel was the medium, the maximum pressure was 154.9 kPa and the maximum impact force peak was 15.999 MN. As the diameter of the tank increased, the maximum pressure of the floating roof impacted by the liquid reduced, but the impact force increased. The slower the turbulence on the inlet relative side, the greater the maximum pressure zone of the floating roof. When the tank volume was 1000 m³, the maximum pressure was 135.5 kPa. When the tank volume was 10,000 m³, the maximum impact force peak was 81.978 MN. Considering the above, a low velocity, a low-density light oil, and an internal floating roof tank with a small diameter are recommended for engineering operations that involve receiving oil. Further increased safety precautions at the edge of the floating roof opposite the inlet are needed. In sum, the findings of the study offer theoretical justifications and a technical reference for optimizing the structural design of floating roofs and the oil receiving and delivering process.