Flavonoid compounds have many benefits in the health field, one of which is xanthine oxidase inhibitor. Xanthine oxidase is a catalyst in the oxidation of hypoxanthine to xanthine and catalyzes xanthine oxidation and causing uric acid formation. The formation of gout in the body will trigger the onset of arthritis gout, which is swelling in the joints, causing unbearable pain. Flavonoid compounds will be extracted from the Sansevieria trifasciata leaves using the Ultrasound Assisted Enzymatic Extraction (UAEE) method which is a combination of two methods, enzymatic hydrolysis in the pre-treatment and sonication extraction process. Enzymatic hydrolysis using cellulase enzymes aims to destroy the cell wall of mother-in-law's tongue leaves so that the yield extraction is expected to be higher. The advantage of using this method is that the extraction time is shorter, can increase the yield extraction, requires a little solvent, and is environmentally friendly. Quantitative tests on the content of flavonoids and inhibition tests of flavonoids on xanthine oxidase will be carried out using UV-Vis spectrophotometry at 415 nm and 295 nm wavelengths respectively. In this study the extraction of flavonoid compounds from the leaves of the tongue-in-law will be carried out using the enzymatic hydrolysis method and sonication extraction with ethanol solvent. The variations of this research are the concentration of cellulase enzymes and the concentration of ethanol solvents. In this study, the optimal extract yield was 58.654% at 60% ethanol concentration and 60 mg/g enzyme concentration. The obtained flavonoid content was 0.370 mg/g in the extract with an enzyme concentration of 60 mg/g and 50% ethanol concentration. The inhibitory activity of the xanthine oxidase enzyme to extract at optimal conditions was 60.267%.