To study the immune and anti-inflammatory activities of Lateolabrax maculatus immunomodulatory peptides (LIP), the preparation conditions of LIP were optimized by single factor experiments and response surface methodology with the stimulation index of mouse spleen lymphocytes as an indicator. RAW264.7 macrophage model was used to study the immunomodulatory effect of LIP, and anti-inflammatory activity of LIP was explored by constructing a lipopolysaccharide-induced RAW264.7 macrophage inflammatory model. The results showed that the optimal preparation conditions for LIP were as following:solid-liquid ratio 1.0∶3.8 (g/mL), enzyme adding amount 2.14%, papain hydrolysis time 56min. Under this condition, the stimulation index of mouse spleen lymphocytes reached 2.57. The results of macrophage immunoactivity show that LIP exerted immunomodulatory activity. 400μg/mL LIP exerted immunomodulatory effects by promoting the proliferation and phagocytosis capacity, nitric oxide and reactive oxygen species production, nitric oxide synthase (iNOS) mRNA expression, and proinflammatory cytokines secretion. Moreover, 400g/mL LIP also showed effectively anti-inflammatory capacity by downregulating prostaglandin E₂ and proinflammatory cytokines, and reducing excessive secretion of NO via inhibiting overexpression of iNOS and cyclooxygenase-2 mRNA. These results suggested that LIP exerted bidirectional immunomodulatory activity,including “increasing immune response” and “inhibiting excessive immune response”, which provided a theoretical basis for bidirectional immunomodulatory functional foods research.