Excessive use of diesel fuel (diesel) sooner or later can cause an energy crisis. With the increase in Indonesia's population, the community's dependence on the use of fuel for both transportation and industrial needs also increases. Therefore, renewable alternative energy needs to be developed in order to reduce excessive use of diesel fuel, namely biodiesel. However, in developing biodiesel there are still shortcomings, namely high vskositas. For this reason, this study aims to improve the quality of biodiesel and to determine the density, viscosity, flash point and calorific value. In this study a mixture of palm oil and Nyamplung oil was carried out using degumming, esterification and transesterification processes. Mixing the two materials was carried out at a temperature of 90 ° C for 60 minutes with variations in the composition of 100: 0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80 , 10:90 and 0: 100 (%). Based on the results of research on the physical and chemical properties obtained the results of the density values in the mixture of Palm oil and Nyamplung oil are in the range of 856,989 kg / m³ to 914,747kg / m³. The viscosity value in the mixture of Palm oil and Nyamplung oil is in the range of 5.1 cSt to 21.1 cSt. The heating value of a mixture of Castor oil and Nyamplung oil are in the range 9543,0998 kal / g to 9260,48055 kal / g. The flash point value of the mixture of Castor oil and Nyamplung oil are in the range of 187.7 ° C to 242 ° C. The higher the composition of the biodiesel nyamplung on the composition of the mixture, the higher the density, viscosity and flash point value produced, due to the density, viscosity and flash point values of nyamplung oil higher than palm oil.