OBJECTIVE:To study the preparation method of the inclusion complex of Decanoyl acetaldehyde(DA)-β-cyclodextrin(β-CD) and the changes of the physical properties of DA before and after being included by β-CD.METHOD:The inclusion complex of DA-β-CD was prepared by milling method.The quantitative method of DA was based upon the formation of chelate compound from DA and copper(Ⅱ) in ammoniacal medium.The chelate was extracted into chloroform and the absorbance of the solution was measured at 300±1nm against a chloroform blank.The solution and dissolution rates of inclusion complex and DA were measured,It were compared the changes ofX-ray diffractin and UV spectrum,and the stability in water between DA and inclusion complex.RESULTS:The molecular ratio of DA to β-CD in the inclusion complex was 1∶1.The solubility of DA in inclusion complex was 11.4times higher than that of pure DA.The parameters of dissolution rate of DA and inclusion complex T_50%were 1.7 and 1.1 min respectively,Td were 3.0 and 1.4min respectively.Their UV spectrum of DA showed no difference.The diffraction peak of DA crystal disappeared after being included by β-CD.CONCLUSION:A new physical phase forms between DA and β-CD.the solubility、dissolution rate and stability in water of DA can be increased,and the bad smell of DA can be masked after being included by β-CD.