Accidents of tank rupture and leakage can be analyzed by numerical simulation. The numerical simulation can be further applied to safety design and accident consequence analysis of oil depot. A CFD based VOF model is developed to simulate the dike overtopping after catastrophic rupture of tank at oil depot. To verify the feasibility and accuracy of this model, a series simulations have been carried out to evaluate the tank failure experiments as per HSE report, and compared with the SPLOT model, wherein, the SPLOT model has been verified to be an accurate model. Analysis have been conducted by using the actual tank dimensions in China so as to study the oil spill process and primary factors of fire dike overtopping. The results demonstrate that the CFD model is more accurate than SPLOT, and the average error between simulation results and experimental values is 5.5%. Analysis also show that the factors of tank volume, fire dike height and oil physical properties have certain but less influence on the final volume of dike overtopping than tank group arrangement and rupture form. (C) 2017 Elsevier Ltd. All rights reserved.