The electrocatalytic oxidation of dopamine (DA) was studied by electrochemical approaches at a carbon ionic liquid electrode (CILE) modified with the composite film of nafion and L-aspartic acid (NL-CILE). The CILE was fabricated by replacing non-conductive organic binders with a room-temperature hydrophobic ionic liquid, 1-butyl-3-methyl-imidazolium hexafluorophosphate. The composite film of NL was used as matrix to adsorb DA and catalyze the oxidation of DA in phosphate buffer solution (PBS). The electrochemical response of DA was investigated at the NL-CILE, the traditional carbon paste electrode (TCPE), CILE and the nafion modified CILE (N-CILE) in 0.1M PBS (pH 7.4), respectively. The results showed the superiority of NL-CILE to N-CILE, CILE and TCPE in terms of provision of higher sensitivity, faster electron transfer and better reversibility. Under optimum condition, the oxidation peak current was rectilinear with DA concentration range from 0.1μM to 0.1mM, with a detection limit of 0.03μM (S/N=3) by differential pulse voltammetry. The proposed method was applied to determine DA in samples successfully.