Abstract: A method of utilizing humic acid to prepare layered humic acid/manganese oxide composite catalyst and its application, the method includes the steps of: adding sodium hypochlorite, manganese salt and humic acid to a water source, stirring and mixing; then introducing into a filter device having a filter material of manganese and a support medium, and generating a layered humic acid/manganese oxide composite catalyst on a surface of the filter material while directing a continuous water flow of the water source into the filter device with a short empty bed contact time for a short time. The catalyst can be used to effectively remove manganese to maintain an effluent with a Mn2+ concentration of not more than 20 ?g/L and to effectively remove heavy metals such as iron, manganese, arsenic, thallium, molybdenum or lead from the water source under neutral, acidic or alkaline conditions with a removal rate of 95% more.