In this work, N-n-amyl-N’-(sodium p- aminobenzenesulfonate) thiourea (APT) containing saturated fatty hydrocarbon group was synthesized. Fluorescence quenching methods in combination with UV absorption spectra and molecule modeling method were used to study the interaction between APT and bovine serum albumin (BSA) or human se-rum albumin (HSA). The binding constants of APT with BSA or HSA were determined at different tem-peratures under the optimum conditions based on the fluorescence quenching results. The binding characteristics of APT and BSA or HSA were reported and the binding sites were obtained. The binding mode was suggested to be mainly hydrophobic interaction, which was consistent with molecular modeling study. In this work, Nn-amyl-N ’- (sodium p-aminobenzenesulfonate) thiourea (APT) containing saturated fatty hydrocarbon group was synthesized. Fluorescence quenching methods in combination with UV absorption spectra and molecule modeling method were used to study the interaction between APT and bovine serum albumin (BSA) or human se rum albumin (HSA). The binding constants of APT with BSA or HSA were determined at different tem-peratures under the optimum conditions based on the fluorescence quenching results. The binding characteristics of APT and BSA or HSA were reported and the binding sites were obtained. The binding mode was suggested to be mainly hydrophobic interaction, which was consistent with molecular modeling study.