Abstract: In order to investigate the effect of dispersibility of SiO₂ nanoparticle on the mechanical properties of SiO₂ nanoparticles/starch film,the aqueous suspension of the SiO₂ nanoparticles,which had been dispersed by the ultrasonic technique in different duration,was observed by atomic force microscope(AFM) and transmission electron microscope(TEM).The mechanical properties of the film varying with the dispersibility of SiO₂ nanoparticles as a result of difficult duration of ultrasonic treatment were examined.The result indicated that SiO₂nanoparticles dispersed by the ultrasonic technique for 50 minutes exhibited good dispersibility and stability,and the film prepared with this dispersion also had optimal mechanical properties.