To investigate the influence of zinc on the growth and composition of Cordyceps militaris, the growth rate and the contents polysaccharide, glucose and zinc were analyzed for both mycelia and fruiting body grown in submerged culture and solid state culture supplemented with Zn2+. Here, we report that increasing Zn2+ alters the growth rate, the contents of both glucose and polysaccharide, and zinc enrichment. Our results show that zinc influences the formation of fruiting body, the biomass of fruiting body and mycelia, the contents of polysaccharide and glucose in fruiting body, and zinc enrichment in mycelia and fruiting body of C. militaris. In submerged culture, zinc at 453-906 mg/L increased mycelia growth. When higher than 4077 mg/L, zinc functions to inhibit mycelia growth. Under the concentration of 4077 mg/L, increasing the concentration of zinc in the medium could enhance the Zn2+ content in mycelia. Fruiting body growth was found increased at highest rate when the medium was supplemented with Zn2+ at 226-453 mg/kg. And the improved growth was associated with higher amount of glucose in C. militaris. The synthesis of polysaccharide increased when fruiting body of C. militaris was grown in media supplemented with Zn2+ at 680-906 mg/kg. Under the concentration of 2038 mg/kg of supplemented Zn2+, the content of zinc in fruiting body of C. militaris elevated along with increasing amount of zinc in media. The zinc content in fruiting body of C. militaris reached the highest level (28570 mg/kg (dry weight)) when 2038 mg/kg of Zn2+ was supplemented in the medium.