The invention provides a preparation method of a platinum catalyst for liquid silicone rubber. The preparation method comprises the following steps: S1, adding sodium bicarbonate into an alcohol solvent to be dissolved; S2, under anaerobic condition, adding chloroplatinic acid, vinyl tetramethyl disiloxane and maleate compound into S1 to react; S3, after reaction of S2 is finished, filtering solid out, washing for many times, combining filtrate, and removing low molecules in the filtrate to obtain the platinum catalyst for the liquid silicone rubber. The prepared platinum catalyst for the liquid silicone rubber disclosed by the invention is applied to the liquid silicone rubber, can effectively adjust activity and speed of addition reaction between vinyl polysiloxane and hydrogen polysiloxane, has excellent catalytic rate, obviously improves operable time of addition type silicone rubber and normal-temperature storage time of the single-component addition type liquid silicone rubber, obviously improves flatness and smoothness of the surface of a cured part after curing and is suitable for single-component or double-component organic silicone adhesives. The preparation method disclosed by the invention has the advantages of simple operation technology, high product yield and suitability for being popularized and applied in industry.