Objective:To determine hydrophilic-lipophilic balance (HLB) value,stability of formulate emulsion and properties of sacha inchi oil.Methods:The physiochemical characteristics of sacha inchi oil were first investigated.Free radical scavenging property was studied by DPPH assay.HLB value of sacha inchi oil was experimentally determined by preparing the emulsion using emulsifiers at different HLB value.Sacha inchi oil emulsion was prepared using the obtained HLB and its stability was conducted by centrifugation,temperature cycling,and accelerated stability test.The efficiency of the prepared emulsion was clinically investigated by 15 volunteers.The primary skin irritation was performed using closed patch test.Subjective sensory assessment was evaluated by using 5-point hedonic scale method.Results:Peroxide value of sacha inchi oil was 18.40 meq O2/kg oil and acid value was 1.86 KOH/g oil.The major fatty acids are omega-3 (44％),omega-6 (35％) and omega-9 (9％).The vitamin E content was 226 mg/100 g oil.Moreover,sacha inchi oil (167 ppm)and its emulsion showed 85％ and 89％ DPPH inhibition,respectively.The experimental HLB value of sacha inchi oil was 8.5.The sacha inchi oil emulsion exhibited good stability after stability test.The emulsion was classified as non-irritant after tested by primary skin irritation method.The skin hydration value significantly increased from 38.59 to 45.21 (P ＜ 0.05) after applying sacha inchi oil emulsion for 1 month and the overall product satisfaction of volunteers after use was with score of 4.2.Conclusions:This work provides information on HLB value and emulsion properties of sacha inchi oil which is useful for cosmetic and pharmaceutical application.