The safety process and effectiveness of in situ burning (ISB) method dealing with spilling liquids depend on flame morphology, mass burning rate and flame radiation. In this work, eight rectangular pools with a fixed area of 400 cm(2) but different aspect ratios (length-width ratio, n = 1, 2, 4, 6, 8, 10, 12, and 16, respectively) are used. As the aspect ratio increases from n = 1 to n = 16, the flame height decreases from 105.6 to 72.9 cm, whereas the incident heat flux increases from 0.283 to 0.562 kW/m(2). The mass burning rate decreases initially at n <= 6 and increases afterwards at n > 6. The traditional flame radiation model overestimates experimental measurement because the radiation model assumes that the flame surface is rectangular, but the actual flame shape shows a trapezoidal surface due to air entrainment. The mathematical linear interpolation method is proposed to make an improvement of rectangular radiation model. The new-proposed flame radiation model is validated by experimental measurements with the relative error < 5%. The current work provides a good method to evaluate the magnitude of loss prevention of oil leakage.