An experimental study is carried out on the combustion characteristics of rectangular heptane pool fire with a fixed area of 400 cm2 but different aspect ratios of (length-width ratio, n) n 1/4 1, 2, 4, 6, 8,10,12 and 16. The results show that the mass burning rate decreases initially and increases afterwards with an increase in aspect ratio. Based on heat transfer theory, the mass burning rate of rectangular pool fires versus aspect ratio is divided into two regimes, namely heat convection and flame radiation coupled regime and heat conduction-dominated regime with a threshold value of aspect ratio n 1/4 6. The flame height has a positive relationship with mass burning rate but a negative relationship with aspect ratio. Based on air entrainment theory, a new correlation of flame height against coupling of mass burning rate and aspect ratio is proposed and validated by experimental observations. The hydraulic diameter is introduced into the classical formula of pulsation frequency, and the experimental and modelling results show that the pulsation frequency of flame height increases linearly with the hydrodynamic diameter ( ffiffi)1 incorporating aspect ratio of rectangular pool in the correlation off f p thorn 1ffinffi (c) 2022 Elsevier Ltd. All rights reserved.