Biodiesel is an alternative energy that is environmentally friendly and has properties similar to diesel oil. One source of vegetable oil that can be used as raw material for biodiesel is Crude Palm Oil (CPO). In the CPO, there are various types of fatty acids such as palmitic acid, oleic acid, linoleic acid, stearic acid, and myristic acid. In this research, biodiesel was synthesized through the transesterification reaction of CPO using a heterogeneous solid catalyst Montmorillonite Nanoparticles (Nano-MMT). The transesterification reaction is the reaction of alcohol with triglycerides to form methyl esters (biodiesel) and glycerol with the help of an alkaline catalyst. The method used in this study was to vary the triglyceride: methanol mole ratio (1:6, 1:9, and 1:12). Through the experiment, the optimum yield of biodiesel was 84,9 grams which was obtained under reaction conditions with a catalyst weight of 4 grams, a reaction temperature of 60oC, a reaction time of 3 hours and a triglyceride: methanol mole ratio of 1:9. The best biodiesel obtained from the yield is analyzed by Gas Chromatography-Mass Spectroscopy (GC-MS). The analysis showed that the biodiesel produced contained 100% methyl ester and there were several kinds of fatty acids.