Ulcerative colitis (UC) is a chronic non-specific intestinal inflammatory disease. Its pathogenesis may be related to heredity， environment， immunity and microorganism. n-3PUFAs are the main components of deep-sea fish oil and they are important bioactive substances in nature. Studies have shown that n-3PUFAs have great potential in the prevention and treatment of UC， but the mechanism is still unclear. The possible mechanism involves the regulation of inflammatory response， oxidative stress， immune response and intestinal flora. This paper makes a review of this in order to provide a theoretical basis for the application of n-3PUFAs in the control of UC.