Marine shellfish are rich in diverse bioactive components, with proteins, small peptides, and amino acids being particularly prominent. These components play a crucial role in the synthesis of hormones and enzymes in the human body, contributing to various physiological functions and offering significant health benefits. Marine shellfish proteins and their bioactive peptides hold broad application potential in the food, dietary supplement, and pharmaceutical industries, especially when processed using technologies like enzymatic engineering and fermentation. However, domestic research and industry still face challenges in maximizing protein utilization, particularly in achieving high-efficiency enzymatic hydrolysis. Protein digestion in the human body depends on a range of enzymes, primarily pepsin in the stomach and pancreatic enzymes in the small intestine. These enzymes break proteins down into smaller peptides, enabling their absorption and utilization by the body. This chapter further explores the digestion process of marine shellfish proteins, their bioactive properties, and their potential contributions to human health.