The phase stability of diesel, ethanol and vegetable oil blends at different component concentrations, as well as the effect of using the blends of various proportions on an internal combustion engine performance has been experimentally investigated. The engine was operated with a diesel ethanol blends from 800 to 1600 rpm for each run. The experimental results of the phase stability revealed that the diesel, ethanol and vegetable oil blends. The experiment was carried out with various blending ratios of diesel, ethanol and vegetable oil blends. The various ethanol concentrations on diesel are 10% and 5% with a vegetable oil of 5% and 10%. The experiment was done with various compression ratios of about 17:1 and 18:1. Where, it attains a higher performance in the compression ratio of 18:1. The performance increases with an increase in load. The experimental results of the engine performance indicated that the equivalence air-fuel ratio and the brake specific fuel consumption for the fuel blends are higher than that of diesel fuel and it increases with the increase of the ethanol and vegetable oil concentration in the blends. In conclusion, among different fuel blends, the blends containing 5% and 10% ethanol concentration are the most suited for CI engines due to its acceptable engine performance and to the fuels solubility.