A pathogenic bacterium was obtained from hepatopancreas of diseased Procambarus clarkii (P. clarkii). The isolated was determined by physiological and biochemical analysis, 16s rRNA sequencing and phylogenetic analysis. Then the sensitivity of the strain and synergistic susceptibility were determined by agar diffusion method and checkerboard assay. The results showed that physiological and biochemical characters similar to Morganella morganii (M. morganii) strain, then 16s rRNA sequence determination and phylogenetic analysis showed that the isolate showed close genetic relationship to M. morganii. Taken together, the strain was identified as a M. morganii strain. The susceptibility study showed that the strain was sensitive to enrofloxacin, florfenicol, neomycin and other 4 kinds of antibiotics, intermediate to kanamycin, resistant to doxycycline, streptomycin, tetracycline and other 9 kinds of antibiotics. Moreover, the synergistic susceptibility showed that doxycycline combined with dihydrocapsaicin had synergistic effect. Taken together, the results demonstrated that the strain isolated from hepatopancreas of diseased P. clarkii is a resistant M. morganii. Florfenicol, enrofloxacin, neomycin and doxycycline combined with dihydrocapsaicin can be chosen as candidate in treating M. morganii infections.