The application of sodium alginate in enteric hard capsule and carrageenan in gastric hard capsule was clarified in this study. Moreover, the structure and physicochemical properties of the gel and rheology of seaweed polysaccharides compound with other polysaccharides, the film-forming of blended polysaccharides and preparation process of plant hard capsule were also summarized. It was reviewed that the researches and applications of film-forming mechanism in plant hard capsule productions in the present paper. The expectation of the future research direction may provide some strategies to the applications of seaweed polysaccharides plant hard capsules.