Abstract: OBJECTIVE To prepared the emodin solid dispersion and to improve its dissolution in vitro and explore its drug release mechanism. METHODS Molecular docking was used to assist in screening polymer carriers. Emodin solid dispersion was prepared by hot melt extrusion using emodin as raw material and Kollidon^® VA64 as polymer carrier. The in vitro dissolution rate of the solid dispersions was measured by stripping apparatus. SEM, DCS and PXRD were used to characterize the surface morphology and crystal shape of the raw material and solid dispersion. Finally, FTIR, NMR and molecular dynamics simulation were used to explore the drug release mechanism of solid dispersions. RESULTS Compared with emodin bulk drug, the dissolution rate of emodin solid dispersion in four buffers was significantly improved, and emodin was transformed from crystalline state to amorphous form, and hydrogen bond was formed between drug and polymer carrier. CONCLUSION The crystal transformation of drug and the generation of hydrogen bond in solid dispersion are the main factors to improve drug dissolution in vitro.