In this paper a research was made on the age，growth and feeding habits of Japanese sea-bass，Lateolabrax japonicus (Cuvier et Valencinnes).Samples were collected monthly from the estuary of Yangtze River in 1986 and 1987. The scales were applied to determine the age of fish. The relationship between its body weight，W ( kg)and body length，L(cm) can be expressed by the formula:W=0. 0605L^2.6346 (r=0. 9878).The relationship between its age，T and length,L can be expressed by the equation:L_t= 100. 9957[1-e^{-0.1768(t+0.7633)}]. The age，T and weight，W relationship can be denoted by theequation:W_t=11542. 26[1一e^{-0.1768(t+0.7633)]2.6346}. The growth inflection point is at t_r=4. 7。corresponding to W=3281. 4gm. This fish is a prodatory one and its feeding habits vary with age. At early young stage it feeds on zooplankton. As the time went on，its foods have relevantly changed and then the foods graduate into shrimps，fish and isopods. The adult feeds on fish and shrimps. Small fish and shrimps are abundant in estuary of Yangtze River and most foods of Japanese sea-bass are smaller fish and shrimps. This may be the reason as it grows up faster than that of other waters. Therefore protaction and propagation of the fishery resources of Japanese sea-bass in estary of Yangtze River are important.