The characteristics of levonorgestrel (LNG), low solubility and the quick degradation under ultraviolet, limited its study and application in rodent contraception. The inclusion complex of hydroxypropyl-β-cyclodextrin (HP-β-CD) with LNG was investigated in present study. The inclusion complex was prepared by solution method and characterized by ultraviolet absorption spectrum and infrared spectrum spectra. And the stability was evaluated by being exposed to ultraviolet. The authors’ results showed that the accurate and simple method of quantitative determination for LNG was established by ultraviolet spectrum, the molar ratio of the complex was 1∶1 calculated from the phase solubility diagram, the stability constant was 187.3 L·mol-1 at 25 ℃, and the formation of the inclusion complex was validated by UV-Vis and Fourier transform infrared spectroscopy. Moreover, the degradation rate of the inclusion complex was less than 5%, which was slower than the LNG monomer. The present study indicated that HP-β-CD could be formed inclusion complexes with LNG and the solubility, and stability were obviously enhanced.