Seven strains were isolated from Pseudosciaena crocea suffering from the skin-ulcer disease cultivated in Xiangshan Area of Zhejiang Province. Strain ZXS01 ,ZXS02 and ZXS07 were confirmed to be the pathogen of the disease by artificial infection test. The traditional physiological and biochemical methods showed that most of the phenotypes of strain ZXS02 were similar to Proteus. In order to investigate the phylogenetic position of this pathogen, 16S rRNA gene was sequenced, its molecular weight is 1495 bp. Molecular phylogenetic dendrogram was constructed based on the genetic distance analysis, which revealed that strain ZXS02 exhibited higher levels of 99.0% similarity to Proteus trdrabilis. Meanwhile, Sensitire （gram negative） identification system was applied in the determination of strain ZXS02, showing 99.96 % similarity with reference strain of P. mirabilis. Based on the results obtained from phenotypes and 16S rRNA gene analysis, strain ZXS02 was identified as P. mirabilis. Furthermore, its sensitivity to 23 antibiotics, temperature and salt were detected, the results showed that it was sensitive to chlommycetin and other 3 kinds of antibiotic, and the optimum temperature and salinity are 37℃ and 20 respectively.