The invention relates to a preparation method of tris[tri(3-sodium sulfonate-phenyl)phosphine]rhodium chloride, which comprises the following steps: adding a tri(3-sodium sulfonate-phenyl)phosphine water solution into a sodium hexachlororhodate hydrate alcoholic solution which has been replaced with nitrogen atmosphere; heating the reactant liquid until the reaction is complete; and separating and recycling the product. The method has the advantages of simple operational process and high yield; and since the sodium hexachlororhodate hydrate, which can be more easily prepared from rhodium powder, is used as the reaction material, the technical process of preparing tris[tri(3-sodium sulfonate-phenyl)phosphine]rhodium chloride from rhodium powder can be greatly simplified, thereby lowering the production cost and having higher economic benefit.