Abstract: OBJECTIVE To prepare hydroxypropyl cellulose-β-cyclodextrin (HP-β-CD) inclusion compound combined with sodium alginate in situ gel combination delivery system. And to improve the stability and water solubility of eucalyptus oil, which is a kind of volatile oil extracted from eucalyptus leaves, as well as to retain the drug in lungs of mice and to release it slowly. METHODS The method of agitation in water solution was applied to prepare HP-β-CD inclusion compound of eucalyptus oil, and sodium alginate was used to prepare ion-sensitive in situ gel. The combination delivery system obtained by adding the inclusion compound to the in situ gel followed by physically mixing. The combination delivery system’s in vitro cumulative erosion rate and the retention property at lungs of Nu/Nu mice was examined. RESULTS The drug-loading rate of HP-β-CD inclusion compound was (6.45±0.16)%; the rate of inclusion was (77.42±1.78)%; the erosion rate of HP-β-CD inclusion-in situ gel combination delivery system was (44.62±2.07)mg·cm^-2·h^-1. In vitro erosion results showed that the delivery system eroded completely in 24 h. In vivo fluorescent image results demonstrated that the delivery system was able to retain in lungs for 12 h. CONCLUSION The combination delivery system can effectively retain at lungs of mice and slowly release drug.