The invention discloses a protection treatment method of tin methanesulfonate solid. The method comprises the following steps: 1, synthesizing: stirring and reacting tin metal with methanesulfonic acid to obtain a tin methanesulfonate solution; 2, preparing a protection agent: uniformly mixing a dispersant OP-10, antioxidants hydrazine hydrate and catechol and a solvent at normal temperature to obtain the protection agent; 3, crystallizing: transferring the tin methanesulfonate solution to a crystallization tank, adding the protection agent, cooling and crystallizing the above obtained material, and carrying out centrifuge dripping to obtain the tin methanesulfonate solid; 4, drying: carrying out vacuum drying on the tin methanesulfonate solid; and 5, packaging: sieving the dried tin methanesulfonate solid, and carrying out vacuum packaging. The method has the advantages of simple and easy process, and prolongation of the shelf life of the tin methanesulfonate solid.