The effects of sample pretreatments on chloramphenicol residue measurement in aquatic products by gas chromatography was studied. Such factors as extraction solvents used , method of extraction , sample cleanup , SPE activation and the derivatization time for chloramphenicol were studied in the sample pretreatment , and also their effects on chloramphenicol recovery were compared in this paper. The experimental results showed that ethyl acetate was the best solvent used for chloramphenicol extraction and n2hexane for lipids removal. The sample cleanup procedure was preferably conducted on a ENVI218 SPE cartridge with water as solvent. The optimal time for derivatization with BSTFA2TMCS was 20 to 30 min. Subsequently , the derivatized chloramphenicol was measured by capillary GC with ECD. The average recoveries ranged from 67 % to 115 % at spiking levels of 0. 1μg?kg -1to20μg?kg -1.