After being onto 22nd recoverable satellite of China for 18-day spaceflight under microgravity condition,the growth and pathogenicity of Penicillium expansum were investigated.Spore germination rate of the spaceflight pathogen was insignificantly lower than that of the ground control.After germination,germ tube elongation of spaceflight pathogen was slower,as well as mycelia growth.However,there was no significant difference according to independent-samples T-test.The consistent results were obtained in vivo.The spaceflight pathogen exhibited a little weaker pathogenicity in peach fruit.These findings suggested that the microgravity reduced the growth and pathogenicity of P.expansum,but the effect was not marked.