Background: Dengue Hemorrhagic Fever (DHF) is a disease transmitted by the Aedes aegypty mosquito. A repellent preparation was found as an anti-mosquito that was practically used by applying it to the skin surface. Plants that can repel mosquitoes are citronella (Cymbopogon nardus) which contains citronellal and geraniol. The preparation used as a repellent is emulgel. Emulgel has emerged as a topical preparation that has two release systems, namely gel and emulsion. Methods: Citronella essential oil was made into an emulgel preparation and the physical properties of the preparation were tested. Then the combination of carbopol 940 and tween 80 was optimized using the simplex lattice design method in Design Expert software version 11. Results: The optimum formula was obtained, namely carbopol 940 at 1.95% and tween 80 at 14.05% with the optimum response result at pH 5.89; viscosity 2247.77cP; and 5.076cm dispersion resulted in a desirability value of 1. Conclusion: All tests of physical properties of the preparation such as pH, viscosity and dispersion met the requirements well and showed significant results. Which means that there is no significant difference between the response predicted by the software and the response generated in the experiment. Verification to ensure that optimization with the software is acceptable.