Abstract: The purpose of this study was to study the influence of hydroxypropyl-β-cyclodextrin on the formation of poloxamer thermosensitive in situ gel. The chemical shifts of EO-CH₂- and PO-CH₃ protons and the thermal changes from the solution to the gel of poloxamer thermosensitive in situ gel in the presence or absence of hydroxypropyl-β-cyclodextrin were determined by variable-temperature¹H NMR and DSC respectively. The chemical shifts of EO-CH₂- and PO-CH₃ protonic moved to low field at T_sol-gel obviously. The temperature of both micellization and gelation was raised from 12. 79 °C and 14. 69 °C to 14. 93 °C and 28. 13 °C with the increase of hydroxypropyl-β-cyclodextrin. It comfirmed that hydroxypropyl-β-cyclodextrin contributed the increased T_sol-gel of poloxamer thermosensitive in situ gel.