Between 1988-1991,13 stains of Flavobacterium were isolated from urine of patients in hospital.The result showed that the strains were gradually increased from year to year.The Flavobacterium was gram-negative,weakly fermentatively saprophytic bacilli,could colonized.These patients had serious underlying disease,such as trauma,diabetes mellitus,congenital heart discase etc.They were immunocompromised and easily infected.Most of the patients had been produced dysbiosis because they had used high doses of antibiotic therapy.The bacteria resistant to many antibiotics and sensitivity test of drug didn't uniformity with the clinical effect so that treatment is very difficulty.Prevention and treatment of the nosocomial infection by this bacteria is important.