Crude oil production and its resources have been restricted today due to its depletion and consumption rate. Biodiesel involves less production cost, environmentally friendly, renewable, non-toxic and biodegradable. In this examination, a novel source likes Cassia javanica has been used as a feedstock for biodiesel utilizing the transesterification process. The impacts in biodiesel on exhaust gas emissions vary depending on the type of biodiesel and petrodiesel. Blends of biodiesel up to 20% mixed with petrodiesel fuels have been be used in all diesel engines and is more easily storage and distribution tools. The purpose of the current study investigates the analysis of biodiesel and their blends with diesel oil in four-stroke ICE applications like unburned hydrocarbons, sulfates, particulate matter, polycyclic aromatic hydrocarbon, carbon monoxide, and nitrated aromatic hydrocarbons. It ended that Cassia javanica methyl ester biodiesel blend (B20) with the addition of SiO2 nanoparticles exhibits a better engine performance and emission reduced compared to fossil fuels. Cassia javanica methyl ester can use directly in diesel engines without requiring extensive engine changes.