The invention relates to a preparation method for a barrier material, in particular to the barrier material suitable for the wall of a percolate equalizing tank. The preparation method comprises the following steps: taking fly ash and ardealite as main raw materials, taking a HAS curing agent and stalk fibers as added materials, mixing the materials, carrying out the dry mixing, carrying out a first wet mixing, carrying out the intermixing, and carrying out a second wet mixing. The preparation method is simple and free in pollution, has a wide range of raw material sources and low cost. The barrier material for the wall of the percolate equalizing tank can effectively solve the defects of cracking, acidic and alkaline corrosion, poor frost resistance, bad barrier property, and the like lying in the wall of the prior percolate equalizing tank, thereby not only greatly improving the crack resistance of the tank wall and simultaneously improving the barrier property, acidic and alkaline corrosion resistance and frost resistance of the tank wall, but also having a simple construction process, easy operation, and the capability of greatly reducing the cost of the percolate equalizing tank.