Abstract: To determine the effect of foreign antigen and mitogen on immune function of tlymphocytes of Paralichthys olivaceus, lymphocytes proliferation induced by haemoglutinin(PHA) and IgG at 16℃,18℃,20℃,22℃ and 24℃ were detected.The proliferation rate of lymphocytes from different flounder lymphoid were analyzed.Lymphocytes obtained from peripheral blood,spleen and head kidney were collected for PHA-stimulated and IgG-stimulated proliferation assay and their proliferation was determined with MTT.Morphology of P.olivaceus lymphocytes after treated with PHA were observe by microscope,we found lymphocytes,lmyphoblasts and mitogenesis in the culture system.The results showed that the proliferation of lymphocytes were decreased sharply at 24℃,within the suitable cultural temperature,from 16℃ to 22℃ in our experiment,at the comparatable low temperature the proliferation of cultured cells were decreased.As compared with those of spleen and head kidney,the proliferation rate of peripheral blood lymphocytes is very high.The rates show no difference between spleen and head kidney.Both PHA and IgG can induce the proliferation of lymphocytes.The nonspecific lymphocyts proliferation(Induced by PHA) of peripheral blood and spleen was significantly higher than that of the lymphocyte from head kidney(p0.05).The specific lymphocytes (Induced by IgG)proliferation of peripheral blood were higher than those of head kidey and spleen(pP.olivaceus.