Abstract: The present study aimed to optimize the ultrasonic wave and cellulase synergistic extraction technology of total flavonoids from Bambusae Caulis in Taeniam and evaluate their antioxidant capacity in vitro. Taking yield of total flavonoids as the metric, the appropriate amount of cellulase added, pH of extraction solvents, ethanol concentration, ultrasonic power, ultrasonic temperature, material-liquid ratio and ultrasonic time were scouted by single-factor experiments, and the optimal conditions for the extraction of total flavonoids from Bambusae Caulis in Taeniam were optimized by response surface methodology (RSM). Meanwhile, the antioxidant capacity was investigated in vitro using scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiaz-oline-6-sulfonic acid (ABTS) free radicals and iron ion reduction method (FRAP). As the result showed that the optimum extraction parameters were the amount of cellulase added: 5%, pH of extraction solvents: 4.7, ethanol concentration: 61%, ultrasonic power: 240 W, ultrasonic temperature: 60 ℃, material-liquid ratio: 1:30 (g/mL), ultrasonic time: 30 min. The total flavonoids yield of Bambusae Caulis in Taeniam was 0.83%±0.02% under these conditions, and the content of total flavonoids in Bambusae Caulis in Taeniam extract was 16.21%±0.42%. The results of antioxidant experiments showed that the total flavonoids could scavenge DPPH and ABTS⁺ radicals with IC₅₀ values of 150.1 and 44.6 μg/mL, respectively, which were 1.22 and 1.27 times greater than V_C. The ferric ion reducing ability of total flavonoids from Bambusae Caulis in Taeniam was slightly higher than that of V_C. This optimized extraction process is simple and feasible, and the extracted total flavonoids shows strong antioxidant effects in vitro, which provides scientific evidence for the further study and exploit of flavonoids from Bambusae Caulis in Taeniam.