To reduce the degradation of inosinic acid in marine fishes for maintaining the freshness of the fish, separation and purification of acid phosphatase (ACP) from Lateolabrax maculatus (sea bass) were performed using NaAc-HAc (pH 5.0) buffer extraction, graded precipitation separation by saturated ammonium sulfate, and anion-exchange column and dextran gel column purification. The enzymatic properties of ACP in the liver of sea bass were studied and potential natural ACP inhibitors were screened using virtual screening and molecular docking techniques. The results showed that two isoenzymes (ACP I and ACP Ⅱ) were isolated and purified. ACP I had a specific activity of 6.57U/mg and was purified to 36.50 times of the original activity with a recovery rate of 9.96%. The specific activity of ACP Ⅱ was 4.62U/mg and it had a recovery rate of 6.07% after being purified to 25.69 times of the original activity. The K_m of ACP I with relatively higher recovery rate and purification factor in sea bass was 3.174mmol/L and v_max was 0.982μmol/(L·min). The optimum temperature and pH of ACP I were 30℃ and 5.0. The secondary structure of ACP I had 14.10% α-helix, 35.00% β-fold, 18.20% β-turn and 32.60% random coil. The five polyphenol compounds as ACP inhibitors were screened virtually, and interacted with ACP mainly by hydrogen bonding and hydrophobic forces. In a certain concentration range (0-1mmol/L), all the five polyphenol compounds could effectively inhibit the ACP activity, and the higher the concentration, the better the inhibition effect. The research could provide a theoretical basis for flavor and quality control of aquatic products during storage.