Abstract: In this paper,the electrodeposition method was used to prepare the glass carbon electrode modified with PHQ/Cu composite film(PHQ/Cu/GCE)and the electrocatalytic oxidation behavior of ascorbic acid(AA)on the electrode was studied by using cyclic voltammetry. The experimental results showed that compared with the bare GCE and PHQ/GCE,PHQ/Cu/GCE had better catalytic activity towards AA,which indicated that the composite film had a good synergistic catalytic action towards the electrooxidation reaction of AA. At the same time,in 0.1 mol/L phosphate buffer solution(pH=4.35),the oxidation peak current of AA was in proportion to its concentration in the range of 5×10^-4~1.0×10^-1 mol/L. The regressive equation was lgI=0.7364lgc+1.6932,R²=0.9959,with a detection limit of 2.0×10^-5 mol/L. The modified electrode was stored in refrigerator for 9 h,the electrochemical signal remained unchanged,and the coexisting substances hardly interfered with the determination of AA,which demonstrated that the modified electrode had good stability and strong anti-interference ability. Furthermore,the modified electrode was successfully used to determine the content of AA in drink with recoveries of 95.5%~109.1%.