Great threats and damages to natural ecosystem and marine environment will be caused once oil and gas leakage occurs. It is crucial to develop a quick response strategy, including the accurate prediction of oil and gas migration path, oil droplet size distribution and other parameters. Volume of fluid (VOF) model and realizable k-epsilon turbulence model are employed to investigate the underwater spreading characteristics and migration law of oil leakage. Influencing factors such as wave length, leakage direction, current speed, wind speed, oil density, and leaking rate are analyzed by numerical simulation. The calculation results indicates that wave length affects both the underwater spread and drift process, while current speed and wind speed mainly influence the drift process. Leakage direction, oil density and leaking rate have significant influence on underwater spread process but limited effect on drift process. A formula is proposed to predict the oil diffusion distance at certain time. The results of investigation can offer a valuable guidance for formulation of emergency response. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.