Liquid-liquid extraction is an effective method for separation, enrichment and detection of combustion promoters at the fire scene. In the liquid-liquid extraction process, the interfacial tension is an important factor affecting the extraction ability. The higher the interfacial tension, the lower the extraction ability. To provide a theoretical reference for the analysis of combustion promoters by extraction method, the effect of interfacial tension on the extraction ability of zinc was studied in this paper. The commonly used amine extractants (primary amine N1923) as well as the phosphonic acid extractants, di (2,4,4-trimethylpentyl)-phosphinic acid (Cyanex272), dialkyl-dithiophosphonic acid (Cyanex302), and dialkyl-dithiophosphonic acid (Cyanex301) were selected in this study. The interfacial tension of zinc ions (ZnCl2) extracted from hydrochloric acid (HCl) was measured, and the interfacial properties of different liquid-liquid systems were studied. The experimental results were analyzed and discussed.