The effect of spaceflight on the physiological and biochemical characteristics of Streptomyces silicium bacterial fertilizer strain was studied.Streptomyces silicium bacterial fertilizer strain was carried by Shenzhou 9 spacecraft for experiment，and the physiological and biochemical characteristics of stain after spaceflight mutagenesis were analyzed，which laid the foundation for the overall technological progress of national microbial fertilizer industry.Results showed that:(1)The loaded strain and CK strain could utilize ten carbon sources and ten nitrogen sources；(2)Both the loaded strain and the CK strain could hydrolyze starch，but neither produced H2S；(3)Under the condition of 4～45 ℃，both the loaded strain and the CK strain could grow，and the growth situation was not significantly different；but at 55 ℃，neither strains could grow；(4)The strains grow well under the condition of pH=6～10 after loading.The CK strains grow well under the conditions of pH=7，8，9.There were no significant difference in carbon source utilization，nitrogen source utilization，hydrolyzed starch，no H2S production and temperature tolerance between the loaded strain and the CK strain，but in terms of pH tolerance，the loaded strain could grow in a wider pH range，had better tolerance，and thus showed stronger stress resistance.