Oil is the main energy resources in Indonesia until right now. Now,fuel oil use fossil from sources non renewable resource. Then, alternative ideaof energy fossil is biodiesel prominent material for diesel engine that produce from vegetable oil. The biodiesel is more strength than diesel fuel. Because, biodiesel has environmentally friendly and non-toxic. Vegetable oil has potentially become alternative energy such as castor oil and coconut oil. However, the researcher uses biodiesel oil are included castor oil and coconut oil. This research has activity mix castor oil and coconut oil with the variation composition and variation mixing times. The variation are 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, and 90:10 (%) during 30 minutes with the temperature 160˚C. The variation mix of time and warm during 30, 60, and 90 minutes for variation of mix 50:50 (%). Based on the result, mix castor oil and coconut oil have kind of mix composition variation. The researcher has the result, if the mixing of mix composition variation gain from that include with heating will affected density, viscosity, flash point and heating values. The fatty acid of coconut oil has longer carbon chain and it has double bond than castor oil. So the coconut can fixed the characteristics of mix fisis. The mixed viscosity of coconut oil and castor oil had been increment with increases composition of coconut oilalthough not fulfill of standard of quality biodiesel.The heat value of coconut oil and castor oil had been decrease with increasingly composition of castor oil, because coconut oil has carbon chain longer than castor oil.