Abstract: The molecularly imprinted polymer(MIP) membrane was fabricated by electropolymerization on the surface of Au electrode, using ascorbic acid (AA) as template molecule and o-phenulenediamine(o-PD) as functional monomer. Organic electrochemical transistor(OECT) sensor with high selectivity and sensitivity for detecting AA was fabricated by using MIP modified electrode as the grid. The MIP electrode was characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The experimental results showed that the best performance of the MIP electrode appeared by using 0.20 mol/L HAc-NaAc as buffer (pH=5.2) with the molar ratio of o-PD to AA of 1:2, and scan rate of 0.5 V/s in potential range of 0-0.8 V after 20 circles. The detection limit of MIP modified OECT sensor was 0.3 μmol/L, and good linear relationship was obtained at concentrations of AA in the ranges of 0.3-3 μmol/L and 3-100 μmol/L.