Provided is a low-molecular-weight holothurian glycosarninoglycan, with the constituent units thereof being a glucuronic acid group, an N-acetaminogalactose group and a fucose group, and a sulfate ester group or acetyl ester group thereof. Glucuronic acid and N-acetaminogalactose are interconnected via β(1-3) and β(1-4) glucosidic bonds to form a backbone of a disaccharide repeating structural unit, and a fucose group is connected to the backbone as a side chain. On a molar ratio basis, the ratio of the glucuronic acid group:the N-acetaminogalactose group:the fucose group is 1:(0.8-1.2):(0.6-1.2). In the structure of the low-molecular-weight holothurian glycosaminoglycan, 10-30% of glucuronic acid groups are modified, on the 2-position, with a sulfate ester group, and the rest are hydroxyl groups; and a proportion of 10-30% of fucose groups is modified, on the 2-position, with an acetyl ester group, and the rest are hydroxyl or sulfate ester groups. The low-molecular-weight holothurian glycosarninoglycan of the present invention has anti-inflammation, anti-vasculopathy, anti-tumor or anti-tumor-metastasis functions, and the effect of improving learning and memory abilities, and can be used for preparing a related drug or health-care product.