Abstract: Aquatic vertebrates live in the water environment with complex and changeable physiological and biochemical reactions. The range of roles which blood plays is very large, such as regulating the physiological and biochemical reactions, maintaining the balance of the organism, ensuring various life activities in an orderly manner. Mucus affords a platform for communication between organism and water environment which is considered as a highly multifunctional material owing to the proposed roles in excretion, respiration, ionic and osmotic regulation, communication, reproduction and protection. The serum and mucus of vertebrates contain a large number of protein components and other biologically active substance as the main bearers of life, which have varieties of function in physiological and biochemical and resistance to pathogenic microorganisms. In order to understand the similarities and differences of the major protein components contained in serum and mucus of aquatic vertebrates, we collected the samples of serum and cutaneous mucus from nine different aquatic animals, such as Chinese sturgeon (Aclpenser sinensis grdy), crucian carp (Carassius auratus), grass carp (Ctenopharyngodon idellus), red-spotted grouper (Epinephelus akaara), banded grouper (Epinephelus awoara), pikes (Esox reicherti), finless porpoise (Neophocaena phocaenoides), yellow catfish (Pelteobagrus fulvidraco) and mandarin fish (Siniperca chuatsi). The concentration of serum and mucus protein was determined by coomassie brilliant blue G-250 method and the protein patterns of serum and mucus from the different aquatic vertebrates were observed by SDS-PAGE. The results showed that the range of serum protein concentration was from 17.88 to 31.60 mg/mL and the mucus was from 1.54 to 3.90 mg/mL. The concentration of serum protein from finless porpoise was the highest up to 68.19 mg/mL which was more than twice the red-spotted grouper having the highest serum protein concentration among eight species of fish. On the other hand, the concentration of mucus protein from finless porpoise was the lowest, only 0.45 mg/mL. Therefore, the finless porpoise possessed the largest ratio of protein content in serum and mucus. The protein patterns of serum from the nine aquatic vertebrates might have significant similarities. There were multiple protein bands distribution in the area between molecular weight of 45 kD and 120 kD. Two bands whose molecular weights were approximately 28 kD and 14 kD appeared in the SDS-PAGE protein patterns of serum from the eight aquatic vertebrates, except banded grouper. Other than the band with molecular weight of about 45 kD, no significant similarity was found among the protein patterns of mucus from crucian carp, yellow catfish, mandarin fish, pikes, grass carp and finless porpoise. It showed significant differences in the protein patterns of serum and mucus from same species of aquatic vertebrates. Among five aquatic vertebrates, pikes, mandarin fish, yellow catfish, crucian carp and finless porpoise, the protein patterns of serum and mucus from yellow catfish had the most similarity, and only 38%. The study may provide new material for the further researching on the features and similarities and differences of protein components in serum and mucus from different aquatic vertebrates.