The invention relates to a preparation method of fly ash stilled bricks, which comprises the following steps: conveying 60% to 65% of fly ash, 10% to 15% of lime, 25% to 30% of fine aggregate in masspercent and 1% to 2% of gypsum in mass percent in the gross mass of the fly ash, the lime and the fine aggregate to a stirring device for first stirring; adding excitant and water to the uniformly stirred materials for second stirring; placing the uniformly stirred materials in a digestion chamber for digestion; rolling the digested materials; pressing and forming the rolled materials through a brick press; palletizing the pressed and formed brick blanks in a still kettle for stilling, maintenance and sintering, and thus obtaining fly ash stilled bricks. The fly ash stilled bricks prepared according to the reasonable matching proportion of the invention have the advantages of energy saving, waste recycling, small density, high strength, favorable water absorption, high temperature resistance, chemical corrosion resistance, good contraction performance, long service life and the like.