With the industry development over these last few decades, there has been an outraged increase in waste products, including toxic compounds in effluents that are highly prejudicial to human health and the environment. Amongst these is aniline is a poisonous, neurotoxin and one of the most important aromatic amines, being used as a precursor to more complex chemicals. It is widely used in various industries such as dye manufacturing, pesticides, rubber chemicals, and pharmaceuticals. Aniline is difficult to remove completely by conventional water treatment or sewage treatment, and therefore, there is a need for a method of using advanced oxidation processes (AOPs) to treat toxic organic compounds. Recently, ferrate(Ⅵ) has been studied by many researchers as an oxidizing agent that can effectively treat various kinds of pollutants. Ferrate(Ⅵ) is a hexavalent iron which can act as a strong oxidant and coagulant in the various pH range and is more oxidative than ozone, hydrogen peroxide(H2O2), and chlorine dioxide(ClO2), which are known as strong oxidizing agents in the acid condition. In this study, the stability of ferrate(Ⅵ) based on Sharma’s method and wet oxidation method and compared the degradation efficiencies of aniline in aqueous solution were investigated. Liquid ferrate(Ⅵ) synthesized by Sharma’s method has more stable than wet oxidation liquid ferrate(Ⅵ). The degradation factors were conducted at different pH, ferrate(Ⅵ) dosage, and an aqueous solution temperature. Moreover, the effect of substituent on the reaction with ferrate(Ⅵ) on the cyclic compounds such as benzene, toluene, 1,4-dioxane similar to aniline were investigated. Aniline was degraded rapidly within 30 seconds by ferrate(Ⅵ). The results indicated that the highest removal efficiency of aniline by liquid ferrate(Ⅵ) was found at acidic condition(pH 4.36). In addition, aniline removal efficiency increased with increasing of ferrate(Ⅵ) dosage, and optimum dosage considered 0.04172 mM. The optimum temperature was obtained in 25℃ of aqueous solution temperature. The intermediate analysis of aniline removal has been conducted using GC-MS. Nitrobenzene, azobenzene, and ρ-benzoquinone were identified. The decomposition rate was different depending on the functional group substituted with benzene. In case of aniline, the NH2 group is more reactive than the CH3 group and H group. Benzene and 1,4-dioxane are no significant difference in the decomposition ratio, but it is considered difficult to decompose into the oxygen atom of 1,4-dioxane.