Polydopamine(PDA) film was modified on the surface of glassy carbon electrode(GCE) by the self polymerization of dopamine(DA).Then the overoxidized polydopamine film modified electrode(OPDA/GCE) was obtained by electrochemical treatment of PDA film in alkaline solution.Furthermore,the chloramphenicol(CAP) concentration was obtained by using square wave voltammetry to detect directly the reduction current of CAP on OPDA/GCE.Self polymerization time of DA,electrochemical response of CAP on OPDA/GCE,electrochemical test condition,and influence and removal methods of dissolved oxygen,etc. were investigated and optimized.The results indicated that the reduction peak current of CAP on OPDA/GCE showed a good linear relationship in the contentraiton range of 3.0×10-6-1.1×10-3 mol/L,and the detection limit was 7.8×10-7 mol/L based on the signal to noise ratio of 3.The recoveries for milk and honey samples were in the ranges of 83.4%-94.1% and 91.5%-108.6%,respectively.The preparation method of the modified electrode is simple,inexpensive and convenient for batch preparation.The detection method of CAP is also simple and high-selective.