Abstract: A HPLC method for determining Tilmicosin in aquatic products was discussed in this paper. The optimal detection parameters were determined by optimizing the analytical conditions; the best procedure and factors of pretreatment were determined in the aspects of extraction and clean-up. Through the experimental verification of different sample substrates, the recovery of standard addition reached 77.22%~93.25% and RSD was less than 5% with the addition of 20~200 μg · kg^-1. Moreover, the limit of quantitation was 20 μg · kg^-1. The results showed that this method had advantages of high test sensitivity, accuracy and wide range of application. It could be used for routine detection and analysis of Tilmicosin residue in aquatic products.