Abstract: Carbon nanotube/cubic nickel cyanoferrate/polyaniline hybrid films were synthesized by cyclic voltammetric electrodeposition of NiSO4, K3Fe(CN)6 and aniline in a H2SO4/Na2SO4 solution on a platinum electrode coated with carbon nanotubes. The electrocatalytic oxidation performance for ascorbic acid (AA) using the hybrid film as an electrode was investigated by cyclic voltammetry and chronoamperometry. The morphology of the film was investigated by scanning electron microscopy. The hybrid film was used for AA detection, and showed a high electrocatalytic activity, a high sensitivity and a low detection limit. The linear range for the detection of AA was from 1×10-5 to 1.4×10-4mol/L with a correlation coefficient of 0.9966, a sensitivity of 654mA·M-1·cm-2 and a detection limit of 6.09×10-6mol/L. The diffusion coefficient and the catalytic rate constant of the electrocatalytic oxidation of AA were studied by chronoamperometry.