To optimize the preparation method of the complex of dihydroartemisinin (DHA) included by hydroxypropyl-beta-cyclodextrin (HP-beta-CD), the molar ratio of DHA and HP-beta-CD, inclusion temperature and inclusion time were optimized by the orthogonal design method with the inclusion drug yield and drug loading as the evaluation indexes. The IR spectrum, DSC and PXRD analyses were employed to characterize the complex and the molecular simulation was processed to investigate the tendency of complex formation. The optimized molar ratio of DHA and HP-beta-CD was 1 : 5, and the optimized preparation was performed under 50 degrees C for 1 h. The IR spectrum, DSC and PXRD analyses indicated the formation of the complex. The low binding free energy and the high solvent accessible surface obtained by molecular simulation showed that DHA could be included by HP-beta-CD and its solubility could be improved significantly. In conclusion, the optimized conditions for the preparation of DHA-HP-beta-CD complex provide a theoretical and experimental basis for further scale-up research.