Bark of Kapok (Ceiba pentandra (L.)) contains tannin, flavonoid, alkaloid, terpenoid, and saponin compounds. Flavonoid known to have inhibitory activity of α-glucosidase. The purpose of this study was to observe the n-hexane, ethyl acetate and water extract of bark of Ceiba pentandra (L.) to inhibitory activity of αglucosidase. The method used for the activity measurement of the fractions was spectrophotometry UV-Vis. Water fraction analyzed by LCMS/MS to identify the chemical compounds. The pure compound suspected analyzed using molecular docking to predict the complementarity related to the model of isomaltase αglucosidase using Autodock Vina, therefore the bond of the antidiabetic active compounds can be predicted. The results show the α-glucosidase inhibitory activity of the bark in n-hexane fraction is 4.60μg/mL, ethyl acetate fraction is 8.55μg/mL and water fraction is 5.61μg/mL. Water fraction analyzed by LCMS/MS eludated at retention time of 3.61min be fathomed as (+) catechin derivate and at retention time of 8.70min be fathomed as vavain derivate. The vavain derived compound, (+) catechin derived compound, acarbose and quercetin each shows docking score of -8.1; -8.8; -6.2 and -7.6 kkal/mol and have similarity to amino acid Glu276 bond which is a catalytic residue that plays role in hydrolysis process. The similarity of chemical bond of the active site be expected to have the same activity as α-glucosidase inhibitory agent.