Nanoparticle TiO2 is a common chemical used in daily life. As increasing usage of TiO2, it is becoming a potentially dangerous contaminant to the environment. However, the impact of TiO2 is not well understood. In this paper, switchgrass was employed to investigate the impacts of nanoparticle TiO2 on plant growth and development as well as the potential impact on the expression of microRNAs (miRNAs). TiO2 significantly affected switchgrass seed generation as well as plant growth and development in a dose-dependent manner. Particularly, TiO2 significantly inhibited root development. miRNA expressions were also significantly altered. Nanoparticle TiO2 may regulate plant development through controlling the expression of certain miRNAs. Among the 16 tested miRNAs, the expression of some miRNAs, such as miR390 and miR399 was increased with increasing TiO2 concentrations; the expression of some miRNAs, such as miR169 was decreased with increasing TiO2 concentrations; the other miRNAs show different expression patterns.