A strain, designated as FM-6, was isolated from fish. Based on the results of phenotypic, physiological characteristics, genotypic and phylogenetic analysis, strain FM-6 was finally identified as Paenibacillus sp. When albendazole was provided as the sole carbon source, strain FM-6 could grow and transform albendazole. About 82.7 % albendazole (50 mg/L) was transformed by strain FM-6 after 5 days incubation at 30 °C, 160 rpm. With HPLC-MS method, the transforming product of albendazole was researched. Based on the molecular weight and the retention time, product was identified as albendazole sulfoxide and the transforming pathway of albendazole by strain FM-6 was proposed finally. The optimum temperature and pH for the bacterium growth and albendazole transformation by strain FM-6 were both 30 °C and 7.0. Moreover, the optimum concentration of albendazole for the bacterium growth was 50 mg/L. Coupled with practical production, 50 mg/L was the optimum concentration of albendazole transformation for strain FM-6. This study highlights an important potential use of strain FM-6 for producing albendazole sulfoxide.