In-situ burning (ISB) has been proven to be a practical way to clean oil on water. The burning behavior of spilled oil is strongly influenced by wind. The flame characteristics of flame base drag and burning efficiency affected by wind speed have been studied through a series of experiments in this study. The wind speeds varied from 0.5 m/s to 2.0 m/s and the inside diameters of the oil pools made from quartz glass were 40 mm, 90mm and 140mm. The variation of fuel vapor density was considered in the dimensionless model for predicting flame base drag length. The proposed formula was shown to correlate with the data of different pool diameters and wind speeds non-dimensionally by Froude number, fuel-air density ratio and the dimensionless heat release rate. The study helped to better understand the fire behavior under wind conditions, and most importantly the developed model would help guide better assessment of the burning in ISB operation. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.