Sebastes schlegelii is an important economic fish cultured in North China. In recent years, S. schlegelii aquaculture has developed rapidly along the northern coast of China. The expansion and intensification of S.schlegelii farming has led to the occurrence of some diseases. In August 2011, an epizootic occurred among cultured S.schlegelii in a cage culture farm in Qingdao, which caused cumulative mortality rate 30%. To make certain the causative pathogen, we studied the etiology and virulence of S. schlegelii so as to provide basic data for the farming industry of S. schlegelii. In this study, we used the morphological, physiological and biochemical methods to identify the isolated bacterium. Meanwhile, to ensure the results accurately, the phylogenetic analyses were also used. A dominant bacterium strain SS-1 was isolated from the skin, gill, liver, spleen, kidney of the diseased S. schlegelii. Artificial infection test with intramuscular injection method proved that the median lethal concentration (LC50) value of bacterium strain SS-1 in S. schlegelii was 9.6×106 CFU/mL. This bacterium could cause severe infections in several tissues and organs of the fish. The results of morphological, physiological & biochemical characteristics tests showed that strain SS-1 was gran-negative, rod bacteria, polar flagellum, and the results of oxidase, contact enzyme, nitrate reduction, producing indol, V-P test and arginine digydrolase test were positive; producing H2S test was negative. The morphological, physiological & biochemical characteristics indicated that SS-1 could be identified as Listonella anguillarum. The sequence analysis of 16S rRNA gene of strain SS-1 was identical with L. anguillarum and the homogeneity is 99%. This paper reported for the first time that L. anguillarum caused the disease of S. schlegelii in China, which will provide reference in fish health management and disease control.