This paper investigates the effect of pool side wall height on flame base drag behavior of pool fires in cross flow of air, which has not been quantified in the literatures. Laboratory-scale experiments are carried out to measure the flame base drag lengths of pool fires using gaseous square quartz sand box as burner of different sizes (10 cm, 15 cm and 20 cm), employing propane as fuel with pool side wall heights of 2 cm, 3 cm, 4 cm and 5 cm above the ground. It is found that flame base drag length is smaller when the pool side wall is higher and increases with increase in fuel supply rate or cross flow air speed, meanwhile decreases with increase in pool size. A new formula is proposed to interpret the evolution behavior that the flame base drag length in relation to these quantities, based on the interaction of cross flow to the buoyancy of the fire. The proposed formula is shown to well correlate the data of different pool sizes and side wall heights non-dimensionally by Froude number, dimensionless heat release rate and the density ratio between the fuel and air. (C) 2016 Elsevier Ltd. All rights reserved.