Abstract: Acid birnessite ( Bir-H) is widespread in soil，oceans，lakes and river sediments，which can determine the behavior and fate of organic pollutants and heavy metals due to its fine particle，large surface area，high amount of negative charge and high surface activity． In this study， acid birnessite was synthesized by a reflux method，and characterized by X-ray diffraction ( XRD) ，scanning electron microscopy ( SEM) and transmission electron microscopy ( TEM) ． The ability of acid birnessite for the removal of methylene blue ( MB) was investigated，and impacts of solution pH， acid birnessite loading，concentration of MB and reaction temperature on the removal of MB were studied． The results showed that the increase of acid birnessite loading and reaction temperature or decrease of solution pH and concentration of MB can facilitate the removal of MB．