The invention provides a method for preparing chabazite from fly ash. The method comprises the following steps: (1) evenly stirring fly ash and solid potassium hydroxide; (2) transferring the evenly-mixed mixture to a high temperature furnace and burning the mixture; (3) grinding the burned alkaline molten substance; (4) adding water and silicon dioxide powder into the grinded substance, and evenly stirring; (5) placing the evenly-mixed liquid into a baking oven to maintain the temperature; (6) after heat preservation, taking out the substance from the baking oven, washing the substance repeatedly until the substance becomes neutral, filtering, and drying to obtain the chabazite. The provided method can obtain cheap chabazite with excellent properties, also processes and utilizes fly ash, saves the resources, and reduces the discharge of pollutants.