Abstract: To explore the bacteriology of chronic suppurative otitis media and diffuse external otitis and examine antibiotic sensitivity of a certain isolated bacterium for guiding appropriate use of antibiotics. MethodsMiddle ear or deep external acoustic meatus purulence were collected from 238 patients with chronic suppurative otitis media or diffuse external otitis and cultured for bacteria, fungi and an antimicrobial susceptibility test. ResultsThere were 206 strains of microbes isolated from the 238 cases. Staphylococcus aureus accounted for 34.95％, methicillinresistant coagulase negative staphylococcus for 20.38％， pseudomonas aeruginosa for 7.28％， and fungi for 18.45％. The antibiotic sensitivity was variable among the isolated bacterial strains. ConclusionStaphylococcus aureus is the main pathogenic bacteria of chronic suppurative otitis media and diffuse external otitis, and methicillinresistant coagulase negative staphylococcus is the second. The infective rate of fungi increased. Pathogenic bacteria have resistance to commonly used antibiotics. We should perform bacterial culture, fungal culture, and antimicrobial susceptibility tests for patients with chronic suppurative otitis media and diffuse external otitis in order to choose appropriate antibiotics.