A field experiment was conducted by spraying silicon fertilizer to elucidate the improving effect on growth and development of fluecured tobacco using K326 as material in Xunyang county of southern Shaanxi province.The chlorophyll content,the net photosynthetic rate（Pn）and stomatal conductance（Gs),nitrogen and potassium contents increased,while transpiration rate（Tr）decreased at topping stage regardless of the spraying time or concentration under silicon fertilizer treat condition.Spraying silicon fertilizer improved the average price,yields,output values and proportion of superior tobacco.Application of silicon fertilizer at rosette stage and two days after topping showed better effect than that at rosette stage and budding stage when supplying with the certain concentration of silicon fertilizer.Moreover,the effect of 3 kg/hm2 silicon fertilizer treatment was better than that of 1.5 kg/hm2 treatment at the same treatment time.The D2 treatment ie.spraying 3 kg/hm2 silicon fertilizer at rosette stage and two days after topping,had efficiently improved the photosynthesis,nitrogen and potassium nutrition,promoted tobacco growth and increased economic efficiency.In conclusion,exogenous application of silicon fertilizer could provide a theoretical basis for promoting growth of tobacco in production of the southern Shaanxi province.