In this study, we used fucoidan (FD), a sulfated polysaccharide, to stabilize zein and obtain a composite nanosystem with better performance that can be used to encapsulate and deliver hydrophobic active substances. The composite nanoparticles of zein and FDwith different mass ratios were prepared by the antisolvent precipitation method. The solution (zein/FD= 1:2) could maintain its stable solution state without precipitation under different environmental conditions (pH 2-8, heating at 80 degrees C for 120min, salt concentration < 25mmol/L and storage at 4 degrees C for 28 days). Subsequently, curcumin (Cur) was used as the model of hydrophobic active substances. When 2 mg Cur was added, the composite nanosystem had a high encapsulation efficiency (81.07%) and could reduce the release of Cur in simulated gastrointestinal digestion. Our results demonstrated that the composite nanosystem prepared by FD and zein, which are both natural biopolymers, has great potential in the encapsulation and delivery of hydrophobic active substances. (C) 2021 Elsevier B.V. All rights reserved.