The invention relates to a preparation method and application of ternary layered transition metal chalcogenide. The ternary layered transition metal chalcogenide has uniform needles and granules on the surface, and the needle diameter and the granular size are 50-150 nm. The ternary layered transition metal chalcogenide is prepared from ammonium tetrathiomolybdate synthesized at room temperature as a precursor in combination with a transition metal compound according to the steps of stirring at room temperature, standing, separating, washing and drying. The prepared ternary layered transitionmetal chalcogenide has high-efficiency, stable and excellent recyclable practical performance in dye adsorption due to characteristics of granule dispersion and multiple gaps, and the maximum saturated adsorption capacity is 679.86 mg/g; and compared with other adsorbents, the ternary layered transition metal chalcogenide has great advantages; and secondly, the ternary layered transition metal chalcogenide has considerable prospects in electrocatalytic hydrogen production, photoelectric conversion, pollutant degradation and the like.