OBJECTIVE: To investigate the facile method for preparation of albendazole sulfoxide, an active metabolite in vivo. METHODS: The reaction condition was investigated according to evaluations to the results of the experiment through temperature, solvent, oxidation agent, reaction time and impurity. RESULTS: The target compound was obtained by oxidation of albendazole with the presence of sodium metaperiodate in glacial acetic acid under low temperature and was free from contamination by impurity albendazole sulfone. Pure product (content >98%) and high yield (>90%percnt;) have been achieved due to reaction selection. CONCLUSION: Oxidation condition is essential to the preparation of albendazole sulfoxide.