Abstract: A numerical model for oil spill in Funing Bay in a marine project construction is established with MIKE 21 Hydrodynamic model and oil spill module in an unstructured grid. Numerical simulations of oil spill in the scenarios of 100 tons fuel oil accidently spilled for 30 minutes starting at 4 typical moments, i.e. flood slack, maximum ebb, ebb slack and maximum flood, are carried out under 3 different wind conditions including the calm wind, the annual dominant wind and the adverse wind. The analyses indicate that the oil spill drift in the sea is mainly affected by the tide and wind conditions, moreover the tide plays a dominant role. The simulated results indicated the area impacted by spilled oil within 24 hours and the shortest time for the spilled oil in concentration of 0.05mg/dm³,which is classified as the first and the secondary grade of national seawater quality, reaching the sensitive objects. The predicted results can provide technical support for marine environmental impact assessment and the decision-making of emergency measures for oil spill accident.