Abstract: We studied the effect of agar-oligosaccharide on the quality of frozen shrimp and tilapia fillets during frozen storage at -18 ℃, based on the indices of dehydration rate, thawing loss rate, cooking loss rate, texture properties, salt-soluble protein contents and Ca2+-ATP activity. Besides, we compared the samples marinated with trehalose and distilled water. Comparing the samples marinated with agar-oligosaccharide and trehalose with those marinated with water and of blank control, the dehydration rate, thawing loss rate and cooking loss rate of the former are lowerer than those of the latter (P0.05), while the texture properties (hardness, adhesiveness, cohesion, springiness, chewiness and fracture force), salt-soluble protein contents and Ca2+-ATP activity of the fomer are better.The indices of the samples treated with agar-oligosaccharide are better than those treated with trehalose. Thus, agar-oligosaccharide can improve the quality of frozen shrimp and tilapia fillets, and have good application prospect in water holding and antifreeze for frozen aquatic products.