•Kudzu starch was successfully modified using OSA.•Interfacial activity of kudzu starch was improved after OSA modification.•Stable O/W emulsions formulation with OSA-modified kudzu starch.•Effects of different environmental stresses on emulsion formulation were studied.•O/W emulsion stabilities were dependent on the concentration of kudzu starch. Kudzu starch esterified with octenyl succinic anhydride (OSA) was used as a food-grade emulsifier to formulate O/W emulsions. In addition, the difference between the physicochemical properties and emulsifying ability of native kudzu starch and those of OSA-modified kudzu starch was investigated. Granules of the OSA-modified kudzu starches increased in size after gelatinization. The interfacial tension between soybean oil and gelatinized OSA-modified kudzu starch was lower than that of kudzu starch. The droplet size of O/W emulsions decreased to 186nm at 100MPa after three passes. The emulsions stabilized using gelatinized OSA-modified kudzu starch were less stable when exposed to different ionic strengths (100mM to 500mM NaCl), than when exposed to different pH levels (2–8). The results of oil droplet size and confocal laser scanning microscopy analysis indicated that emulsions containing 2–5% OSA-modified kudzu starch remained stable at room temperature for 30 days.