Three oil spill models were briefly reviewed. And based on the analysis of problems and defects existing in “Oil Particle” approach, a “TwoStep” method was put forward for oil spill simulation. The method divides oil spill movement into two steps: selfexpansion and turbulent expansion. The former step was handled by refinement of Fay’s equations, while the latter was handled by “Oil Particle” approach. Numerical experiment results show the “TwoStep” method can make up the shortcomings of “Oil Particle” approach and accords with the reality that spilled oil has different diffusion mechanism in the process of movement. 