An electroanalysis method of determining Chloramphenicol (CAP) based on the eletrocalysis property of DNA-hydroxyapatite modified electrode (dsDNA/HAp/GCE) was setted up. In KH2PO4-Na2HPO4 buffer solution with pH 6.0 cotaining 0.1 mol·L-1 KCl, the peak current was proportional to the concentration of CAP in the range of 2.80 × 10-7 to 3.60 × 10-6 mol·L-1, with a detection limit of 1.35 × 10-7 mol·L-1. The linear regress equation was ip (μA) = 5.865 + 0.4784 c (µmol·L-1), and the linear correlation coffcient was 0.9942. The method has been successfully applied to the quantitative analysis of CAP in real Chloramphenicol eye drops samples, which totally meet the demand of microanalysis. The relative standard deviation samples analysis results was 1ess than 3%.