Objective: To prepare solid dispersions of baicalin-PEG 4000 and investigate dispersed state and thermodynamic properties in melting process of baicalin. Method: Solid dispersions of baicalin-PEG 4000 was prepared by melting method

thermodynamic parameters in melting process of baicalin in solid dispersions and physical compound were determined by differential scanning calorimetry method. Result: Melting enthalpy of baicalin in solid dispersions was smaller than that in physical compounds

but phase transition cooperativity of melting process in solid dispersions was larger than that in physical compounds.All thermodynamic parameters of melting process in solid dispersions including melting temperature

melting enthalpy

and melting phase transition cooperativity increased with increasing the concentration of PEG 4000. Conclusion: Baicalin existed as minicrystal in solid dispersions and increasing the concentration of PEG 4000 will make baicalin more homogeneous.