Abstract: As a metal nanoparticles,ZnO nanoparticles (ZnO NPs) has been applied in agricultural production gradually due to its unique physical properties and larger specific surface area.In order to understand the effects of ZnO NPs on maize growth,seven different concentrations of ZnO NPs (10 mg·L^-1,20 mg·L^-1,50 mg·L^-1,100 mg·L^-1,200 mg·L^-1,500 mg·L^-1,1 000 mg·L^-1) with shake immersion method were used to investigate their effects on seed germination and root carbon metabolism in maize.The results showed that lower concentration (20 mg·L^-1,50 mg·L^-1,100 mg·L^-1) ZnO NPs shortened the germination time and increased the germination rate; the germination rate with 50 mg·L^-1 treatment was the fastest.The total germination,germination energy,germination index and seed vigor index increased and then decreased with the ZnO NPs concentration increasing; and all indexes with 50 mg·L^-1 treatment reached maximum values.Low concentrations (50 mg·L^-1,100 mg·L^-1) ZnO NPs significantly increased root and shoot growth and elongation,favorable to biomass accumulation.In addition,ZnO NPs (50 mg·L^-1) significantly increased the activities of hexokinase and UDP-glucose pyrophosphorylase while reduced the aldolase activity,providing metabolites and energy for seed germination and growth.Therefore,50 mg·L^-1 ZnO NPs promoted glycolysis and cell wall biosynthesis,which would be conductive to enhancing seed germination and seedling vigor.