Abstract: Falling film evaporation is the core heat transfer mode of spiral-wound heat exchangers used in the liquefaction process of natural gas. In order to study the impact of different Reynolds numbers, outer diameters and spacings of pipeline on the parameters of the falling film flow of alkane media, such as the flow pattern and liquid film thickness, numerical simulation study of falling film flow was performed with the coupling model based on the VOF and Level Set two-phase flow models. Meanwhile, the numerical simulation model was verified by setting a visual experimental device. In addition, the calculating equation of liquid film thickness applicable to the alkane media was obtained by fitting based on the numerical simulation results. According to the results, the Reynolds number and the outer diameter of pipeline have great influence on the distribution of liquid film thickness. In the case that the outer diameter of pipeline is 4 mm, the liquid film thickness of falling film flow is uniform with poor stability at great Reynolds number (340–1 700). In general, the research results could provide theoretical guidance to the design and the safe and efficient operation of spiral-wound heat exchangers during the liquefaction of natural gas.