The invention discloses a preparation method of a wood-grain brick with a wood-knot effect. The preparation method comprises the following steps: A, preparing materials: a1, preparing two or more clays which are consistent in drying rate and shrinkage rate, have a contrast effect in color after baked, and are 10 to 20 percent in water content; a2, preparing particle clusters containing non-uniformly-mixed pigments; B, feeding materials: putting raw materials, in proportion, into an extruder provided with spiral blades according to the required color contrast degree, putting the clay serving asbottom color first, putting the particle clusters intermittently after the clay is put into the extruder fully, putting the clay serving as grain, putting the particle clusters intermittently, then putting the clay serving as the bottom color, putting the particle clusters intermittently, putting the clay serving as grain, repeating the steps above and repeatedly, continuously and alternatively feeding; C, extruding and molding; D, performing drying and baking to obtain wood-grain bricks with wood-knot effect. By adopting the preparation method of the wood-grain brick with the wood-knot effect, the technical problem that an existing conventional extruding-molding wood-grain brick cannot have a wood-knot simulation effect is solved.