Spill fires usually occur with liquid fuel storage and transportation, which may pose a threat to process safety and environmental protection. Analysis on the liquid layer spread and burning behavior is vital for preventing and mitigating spill fire accidents. In the study, a number of heptane continuous spill fire experiments on a fireproof glass sheet were conducted to better understand the spreading and burning of continuous spill fires. In the experiments, the liquid surface area, burning rate and heat transfer between liquid layer and the glass sheet were analyzed. The results showed that the heptane burning rate of spill fires was lower than that for pool fires of the same burning size. The experimental data showed that the radiative penetration through the liquid layer was mainly responsible for the lower burning rate at the quasi-steady burning phase. Based on the heat transfer process, a modified burning rate model of spill fires by considering the heat loss of liquid layer was developed and validated by the experimental data. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.