The aim of this work is to decrease emissions in compression ignition engines fueled with diesel and biodiesel blends and also addition of coconut shell (CS) nano particles were prepared by mechanical ball milling process. The organic nano particle was characterized by Transmission Electron Microscopy (TEM), and energy dispersive analysis of X-rays (EDAX) technique. The biodiesel was prepared by using Pungamia pinnata non-edible oil through transesterification process. The average particle size of coconut shell nano particles was found as 20 nm in diameter. Without changing the engine design the performance and emission test was conducted in single cylinder diesel engine with fuels of 100%DF, 20%BD80%DF and 20%BD80%DF with CS.