Abstract: OBJECTIVE To investigate the formulation stability and influence factor of clarithromycin emulsing. METHODS The particle size, pH reduction and drug content were used as the indexes to investigate the clarithromycin emulsion stability in different storage temperature. RESULTS The drug loaded emulsion was stable when at low storage temperature. As the storage temperature increased, the particle size of clarithromycin emulsion increased significantly. And lead to pH reduction. Based on Arrhenius equation, T_0.9 would increase to 9.06 years, when storage temperature was 5 ℃. Long term stability testing results indicate that the physical and chemical properties of clarithromycin emulsion was stable within 12 months. CONCLUSION Low storage temperature is hepful to improve the formulation stability.