Ethanol can be used as a solvent for stannous octoate. Sodium hydroxide solution reacts with isooctanoic acid, then rhodium-doped supported antioxidant is added to react with stannous chloride in nitrogen atmosphere, and the quality and stability of the product are greatly improved. In the preparation process, adding rhodium-doped supported antioxidant is not only beneficial to increase the content of divalent tin in the product, but also helpful to improve the conversion rate. This process fills the blank of production technology in this field. The products produced can completely replace imported products, saving a lot of foreign exchange for the country.