In this paper, the mechanical and morphological properties of biodegradable SAN/EOC/Nanoclay/Proteins nanocomposite were investigated. The composites were first prepared by a laboratory-scale twin screw extruder. Morphology of the blend was determined by SEM images. Mechanical properties in terms of tensile tests were carried out by Testometric TS2000, stress at break, strain at break, and Young’s modulus was determined. Based on mechanical results, although the young’s modulus increases with increasing protein content but the strain at break of the composite decreases acutely because of the presence of protein. The blend indicated an improvement in mechanical and thermal properties. Today, according to the vast application of plastic in different fields, environmental issues were affected by these kinds of non-degradable materials, so that biodegradability of the plastics is just the remaining route to solve. In this research, biodegradable blends were prepared using whey protein as a biodegradable natural polymer. The results of the biological procedure-test after 3 months indicated sufficient weight loss and biodegradation of these blends.