The invention discloses filler prepared by using a P1-type coal ash molecular sieve. The filler comprises the following components in weight percentage: 55-75 percent of coal ash, 5-10 percent of straw carbon, 4-8 percent of sodium silicate and 5-10 percent of Hangjin clay. The invention also discloses a method for preparing the filler. The filler disclosed by the invention is simple in process, easy in control and low in cost, is in favor of treatment of three wastes and is of great importance in polluted environment treatment.