Diesel engines dominate the field of commercial transportation and agricultural machinery on account of its superior fuel efficiency. Cost and limited reserves of conventional fossil fuels have intensified the search for alternative fuels for use in internal combustion engines. A possible alternative engine fuel is vegetable oil because it is clean burning, renewable, non-toxic, biodegradable and environmetally friendly transportation fuel. It can be used in neat form without any modification of the engine. They can be produced from the plants grown in rural areas. Vegetable oils are produced from crops such as soybean, peanut, sunflower, cotton, jatropha, mahua, neem, coconut, linseed, mustard, karanja, rape and castor. Evaluate the performance characteristics and combustion parameters of vegetable oil esters like Jatropha, Mahua and Neem for the various injection pressure and they are compared to diesel fuel. The diesel fuel results were compared with vegetable oil ester. Finally it was concluded that the performance of vegetable oil esters such as Jatropha, Mahua, and Neem are much better than diesel.