The intermolecular interaction between Icarrin (ICA) and Human Serum Albumin (HSA) was investigated by spectral method and building molecular model to explore ICA-HSA mechanism of interaction. And the intermolecular interaction model of ICA-HSA was described by using a variety of theoretical equations to compare and discuss their usability. The results showed that the fluorescence intensity of HSA in the fluorescence spectra showed regular decrease, indicating that HSA did interact with ICA. The synchronous fluorescence spectrum showed that micro-conformation of HSA changed due to the intermolecular interaction between ICA and HSA. The intermolecular interactions of ICA-HSA were described using Stern-Volmer equation, Lineweaver-Burk equation, double logarithmic regression equation, Scatchard series equation, Lehrer-Fasman equation and Tachiya model respectively. The results showed that the theoretical model was different and the results were different from ICA-HSA. There are two quantitative kinds of trends based on the differences between hypothesis and experimental conditions. In this paper, physical model was built to assist the intermolecular interaction mode of ICA-HSA.The optimal mode of ICA-HSA intermolecular interaction was the double logarithmic equation. Meanwhile, the ICA-HSA intermolecular interaction was analyzed by physical modeling, indicating that the ICA tend to occurr in active site Sudlow’s sites I and ICA-HSA system mainly has van der Waals force, hydrophobic interaction and hydrogen bonding. These results obtained in this paper serves to provide a reference for the comprehensive analysis of ICA-HSA intermolecular interaction, as well as the theoretical description of the intermolecular interactions between small molecules and biomacromolecules.