The invention relates to the field of a pesticide preparation, discloses an insect-killing and disease-preventing suspension seed coating formulation, and relates to a suspension seed coating formulation mixed by dursban and fludioxonil serving as effective components and a preparation method thereof. The suspension seed coating formulation comprises the following components in percentage by weight: 3.0 to 25 percent of chlorpyrifos, 0.5 to 20 percent of fludioxonil, 1.0 to 8.0 percent of wetting dispersant, 1.0 to 10.0 percent of film forming agent, 1.0 to 10.0 percent of coloring agent, 0.1to 2.0 percent of tackifier, 1.0 to 5.0 percent of antifreezing agent, 0.1 to 1.0 percent of preservative, 0.1 to 1.0 percent of antifoaming agent, and the balance of distilled water. The suspension seed coating formulation has the advantages of good pesticide effect, long persistent effect, high work efficiency, economy and safety, so that the environmental pollution can be reduced, the pesticide utilization is improved, and the pesticide usage is reduced. The seed coating formulation is convenient to use, can perform mechanical seed stirring and manual operation when processing seeds, so that the requirements of different users can be met.