Abstract: A composite gel system was established by adding 0, 0.2, 0.3 and 0.4 g/mL sucrose (SUC) in Enteromorpha prolifera polysaccharide (EP), respectively. The rheological properties of the composite gel were analyzed by automatic rheometer, and the structure of the composite gel was analyzed by fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) to investigate the interaction between the two. The results showed that EP gel was a pseudoplastic fluid, and the fluid properties of EP were not changed after the addition of SUC. However, the viscosity, G′, G″ and tanδ of EP gel mixed with 0.2~0.3 g/mL SUC was significantly increased (P<0.05), indicating that the SUC could significantly improve the viscoelasticity of EP. In addition, thixotropy and water holding capacity of the gel mixed with 0.3 g/mL SUC was significantly increased (P<0.05). The results of structural analysis showed that there were strong hydrogen bonds among SUC, water, and EP molecules. The microstructure showed that the addition of 0.3 g/mL SUC made the EP gel matrix finer, the cross-sectional structure was flatter and less porous. When the SUC concentration reached 0.4 g/mL, the hydrogen bonds maintaining the EP gel structure were reduced, and the gel density, viscoelasticity and water holding capacity were decreased. In this study, 0.3 g/mL sucrose promoted the formation of stronger, water-holding, and stable gel structure of EP, which would provide a theoretical basis for further high-value utilization of marine green algae resources.