The aim of this work was to investigate enzyme-assisted ultrasonic extraction of Shaanxi Polygonatum sibiricum and their anti-oxidant and anti-A549 proliferation activities in vitro.Based on the single factor test,Box-Behnken experimental was adopted including dependent variables(cellulase amount,ethanol concentration,ultrasonic time and solid-liquid ratio) and independent variable(yield of flavonoids).The results showed that the optimum conditions were cellulase amount 2%,ethanol concentration 90%,ultrasonic time 20 min,and solid-liquid ratio 1∶16(g/mL).The yield of total flavonoids reached 103.10 ± 0.02 μg/g.The method was simple,feasible and repeatable.High performance liquid chromatography(HPLC) analysis showed that the flavonoids contained 6.43±0.25 μg/g quercetin dihydrate and 92.31±1.75 μg/g baicalin.The EC₅₀ of total flavonoids on scavenging DPPH free radical,hydroxyl free radical and ABTS were 11.20,57.88 and 23.75 μg/mL respectively,which indicated that total flavonoids from P. sibiricum had strong anti-oxidant capacity.CCK-8 tests showed that the IC₅₀ of total flavonoids treating on A549 cells was 25.18,12.52 and 9.25 μg/mL at 24,48 and 72 h respectively,which indicated that total flavonoids from P. sibiricum could inhibit the proliferation of A549 cells in a dose- and time-dependent manner.