Duralium has mild character, high ductility, and resistance from corrosion. Doing heat treatment against this alloy by cooling variation can increase strength and ductility of this alloy. Cooling media variations which is used for this research are 10% dromus oil + water, 20% dromus oil + water, and 30% dromus oil + water. The purpose of this research is knowing the tensile strength of duralium in artificial aging process against cooling media variation 10% dromus oil + water, 20% dromus oil + water, and 30% dromus oil + water, type of fracture, and phase changing of duralium. This research include in experimental research category which uses the one-shot case study research model. Tensile testing uses Hung Ta Instrument machine and type of fracture is observed from micro and macro photo of duralium. The aging result shows that tensile strength of duralium increase from 8.3304 Kg/mm2 to 8.6229 Kg/mm2. This is due from aging result which is formed precipitates evenly due to the difference of cooling media ...