Objective To study the alteration of microbial population distribution and resistance of clinical bacterial isolates in patients with severity muhiple injuries. Methods The distributed Features of 432 strains of infection germs detected among the patients with severe muhiple iniuries admitted into hospital from January 2004 to December 2006 were statistically analyzed during. Results In the total 432 strains,the G accounted for 62.9%(272/432),dominated mainly by pathogens including Pseudomonas aeruginosa,Acinetobacter baumanni I and Escherichia Coli.The G+accounted for 37%(160/432),mainly including Staphylococcus anreus,enterococci and coagulase negative staphylococcus (CNS).Mixed infection rate was 41.1%.The isolating rate of enterococci.CNS and Sten Matophilia was obviously upgraded. Conclusions The source of infection in patients with severity multiple injuries is Gram-negative bacterium,suggesting that surveillance of bacterial resistance and rational use of antimicrobial agents should be emphasized during clinical therapy.