The aim of this work is to decrease emissions in diesel engines fueled with diesel and algae biodiesel blends and also addition of BiO nanoparticles. Azolla algae can be used to produce biodiesel, because of high oil content. The biodiesel was prepared by using Azolla algae non-edible oil through transesterification process. In the present study, the BaO nano additives into the algae oil-based methyl ester blend and its diesel blends are analyzed the emission characteristic at different load. Addition of BaO nanoparticle was a strategy to reduce emission (CO, HC, and O-2) of the biodiesel.