The invention provides a surface modification method of a supported platinum catalyst, relating to a method for enhancing the stability of a supported platinum catalyst under high-temperature service conditions by modifying a silicon-base inert layer. The scheme is as follows: the method comprises the following steps: 1. raw material preparation; 2. primary roasting; 3. secondary roasting; 4. first mixed solution soaking; 5. first acidic water solution soaking; 6. repeated operation; and 7. final roasting. When the supported platinum catalyst treated by the modification method is used under high-temperature conditions for a long time, the high-temperature aggregation resistance of the platinum metal component is greatly enhanced. Due to favorable high-temperature aggregation resistance, the product has favorable application prospects in catalysis. The method provided by the technical scheme of the invention has the advantages of simple operation in every step, lower equipment cost, lower environmental protection cost, high operational safety and lower personnel shielding cost.