Bioactive substances from marine resources are usually found and used for human life, and almost active substances are detected belong to polymer groups possessing value biological activities, for example, antioxidant, anti-fungal, anti-HIV, anti-cancer, etc., originated from animals and plants (seaweeds, sponges, sea cucumbers, fish, crabs, shrimps). Marine biological polymers which are known such as many alginates, fucoidan, phlorotannin, chondroitin sulfate, laminarin, chitin, chitosan, astaxanthin, carrageenan, agar, ulvan, lectin, etc, are the diverse of structure and biological activities with great application ability in different fields, for example, food, functional food, pharmacy, etc. However, the exploitation, production, and trade of marine biopolymers are not commensurate with their inherent potential. Special Issue gives an overall picture on marine biopolymers basing on aims and scope (Extraction and optimization; Biological activities and application; Biological activities and application; Biological membrane; Marine biological polymer in processing and storage), and the spirit of scientific cooperation in the field of marine biopolymers. Exhibiting the extraction techniques, structure characteristics, and polymer application into food will be clearly and especially. Good ideas and new solutions related to marine biopolymers in different parts of the world will appear to help the study and use of marine biological polymer more and more effective.