A preparation method of Dipotassium Tetrachloroplatinate , the preparation process is as follows: using sponge platinum as raw material to prepare chloroplatinic acid solution and potassium chloride solution to prepare Dipotassium Tetrachloroplatinate , and then using hydrazine hydrochloride as reducing agent to reduce chloroplatinic acid Potassium for the preparation of pharmaceutical intermediates Dipotassium Tetrachloroplatinate . Include the following steps: a) Preparation of Dipotassium Tetrachloroplatinate : Weigh a certain amount of sponge platinum, put it into a beaker after washing, add an appropriate amount of aqua regia in batches, and heat appropriately. The reaction process is based on the principle of uniform bubbling. After the reaction was stopped, concentrated hydrochloric acid was added dropwise under heating and boiling to catch the nitrate until the system no longer took brown nitrogen oxides, and then an appropriate amount of water was added to catch the acid. After filtering, the filtrate was heated and concentrated to the desired concentration, and then cooled. Accurately weigh a certain amount of potassium chloride, dissolve it in water to make a 15%-30% solution, filter, and use the filtrate for later use. Take an appropriate amount of the above chloroplatinic acid solution and add it dropwise to the potassium chloride solution under stirring, and the solution will appear yellow precipitate. After the dropwise addition, continue to stir for about 1-2 hours to complete the reaction. After filtration, the obtained precipitate was washed with deionized water to neutrality, and the washing solution was concentrated and recovered. Vacuum dry at 70-90℃, and the product will be ready for later use after passing the test. b) Synthesis of potassium chloroplatinite: prepare 20%-35% hydrazine dihydrochloride solution. Take a certain amount of potassium chloroplatinate in step (a) and put it into a flask, add distilled water, heat to 60-80° C., and stir. Using a constant pressure funnel, the reducing agent hydrazine dihydrochloride solution was added dropwise to the potassium chloroplatinate suspension to carry out the reduction reaction. After the dropwise addition, the reaction was continued for 2-3 h, cooled, and the mixture was filtered to obtain insoluble matter and scarlet filtrate. c) drying of product and recovery of precious metals: in step (b), the insolubles are potassium chloroplatinate and platinum black, which are recovered. The filtrate is potassium chloroplatinite solution, and the filtrate is evaporated and concentrated until potassium chloroplatinite crystals appear, then vacuum-dried at 50-60 ° C for about 1 hour to obtain a dark red potassium chloroplatinite product. Samples were taken for total elemental analysis and XRD testing. In the method of the present invention, the concentration of described potassium chloride is 15%-30%, and optimum is 20%; Vacuum drying temperature is 70-90 DEG C, optimum is 80 DEG C. In the method of the present invention, the reducing agent is hydrazine dihydrochloride, the concentration is 20%-35%, the optimum reduction temperature is 60-80°C, and the optimum is 75°C. Weigh 100g of platinum sponge, put it into a beaker after washing, add an appropriate amount of aqua regia, heat appropriately, and the reaction process is based on the principle of uniform bubbling. After the reaction is stopped, the obtained solution is concentrated to have crystals to separate out, and concentrated hydrochloric acid is added dropwise to catch the nitrification until the system no longer takes brown nitrogen oxides, and then concentrated until there is crystallization to separate out, and an amount of deionized water is added to catch the acid. Filtration, and the filtrate was prepared into a 50g/L solution for later use. Weigh 80.0 g of potassium chloride to prepare a 20% solution, filter, and use the filtrate for later use. The above-mentioned chloroplatinic acid solution was taken and added dropwise to the potassium chloride solution under stirring, and the solution appeared yellow precipitate. After the dropwise addition, continued stirring for 1-2h to complete the reaction. Weigh 200g of potassium chloroplatinate into a 4L beaker, add 1500ml of distilled water, stir, heat to 75°C, dissolve 22g of hydrazine hydrochloride in distilled water to prepare a 25% hydrazine hydrochloride solution, and use a constant pressure funnel to remove the hydrazine hydrochloride solution. Add dropwise to potassium chloroplatinate. After the dropwise addition, continue stirring and heating for 2-3h. After cooling, the mixture was filtered, and the insolubles were collected in a concentrated manner. The filtrate was scarlet, evaporated and concentrated until crystals appeared, and then vacuum-dried at 50° C. for 1 h to obtain dark red potassium chloroplatinite crystals. The product is easily soluble in water, clear after dissolving, no inconsistencies visible to the naked eye, eld is 95.5%. The crystal was sampled for full element analysis and XRD detection, platinum content: 46.9%, potassium content: 18.5%, and no compounds other than potassium chloroplatinite were detected.