Many studies have been accomplished in the field of nanocomposite (NC) preparation to control the adhesion and spatial dispersion of nano-fillers and effect of these on attributes of the polymer matrix. In this investigation, surface modification of alpha-Al2O3 nanoparticles (NPs) was performed by vitamin B-1 (VB1) as biodegradable and environmentally friendly modifier agent. Poly(vinyl chloride) (PVC) NCs were prepared with several contents of modified alpha-Al2O3 NPs (3, 5, and 7 wt.%) by ultrasonication method. Then, many standard techniques were used to study the properties of NC films. The results demonstrated that PVC/alpha-Al2O3-VB1 NC films had better thermal stability and stress strength properties than pure PVC. Morphology images of PVC/alpha-Al2O3-VB1 NCs showed the good dispersion of NPs in the polymer matrix in nanometer scale. They revealed that the alpha-Al2O3 NPs have sphere-like morphology. The mechanical properties of PVC/alpha-Al2O3-VB1 NCs were improved by adding different amounts of alpha-Al2O3-VB1 into the matrix of PVC. Water contact angle analysis showed increase in hydrophilicity of PVC/alpha-Al2O3-VB1 NCs.