Abstract: The extraction of tyrosine from hydrochloric acid medium was studied. In the experiments sodium dodecylbenzene sulfonate acid was chosen as extractant, kerosene as solvent and TBP as additive agent. The effects of temperature, pH and extractant concentration on the distribution coefficients of tyrosine were discussed. The optimum conditions of extraction and stripping are obtained. The entropy changes in extracting and stripping reaction are -9.23kJ/mol and 11.2kJ/mol respectively. The sodium dodecylbenzene sulfonate of extraction and stripping numbers of theoretic stages are 5 and 4 respectively.