The effect of different winter wheat residue treatments (returning straw, RS; high stubble with mulched, HS and zero stubble, ZS) on activities of microorganisms in rhizosphere of summer maize（Zea mays L.）was studied in 2005 and 2006 at 3 places via field testing. The results indicated as follows: The content of rhizosphere microorgranism and enzyme activities of protease and urease in soil of 3 treatments above increased first , and then descended and reached maximum at silking stage. Among the treatments ,these indexes of RS were the higest and these of ZS were the lowest. Furthermore the differences between treatments during growth periods were different : It was highest in the seedling stage and then the differences reduced with the increase of growth period . The changes in soil CO2 flux showed the similar trend to indexes mentioned above.