The invention provides a preparation method of tiles with imitated natural stone grains.The preparation method comprises the following steps that 1, color pastes are prepared, wherein the pastes of at least two colors are prepared by selecting common raw materials for ceramic bodies and adding ceramic pigments through wet ball milling; 2 premixing is conducted, wherein the color pastes are unevenly mixed to obtain an uneven paste; 3, the uneven paste is applied to tile green bodies to form pattern layers; 4, the tile green bodies obtained in the step 3 are placed in a kiln for sintering, and then the tiles with the imitated natural stone grains are obtained.According to the preparation method, strip-shaped intersection or staggered mixing is formed between the color pastes through an uneven mixing method, the paste is applied to the pattern layers formed on the tile green bodies, multiple different pattern grains such as a strip shape, a flocculent shape and a pinnate shape can be presented, the prepared tiles with the imitated natural stone grains have the decorative effects of different patterns and lines, the grains are rich and diverse, different in style and clear and vivid in effect, and therefore the diversity of the decorative effect is improved.