The invention relates to the field of deep processing of tin, in particular to a process for preparing stannic chloride. The process comprises the following steps: tin particles are melted; a fluid formed after melting of the tin particles is perpendicularly sprayed to the surface of a roller rotating at a high speed from top to bottom through a spray nozzle; the fluid is thrown to an atomization chamber on one side due to rotation of the roller, and tin drops are formed; chlorine is introduced to the atomization chamber from bottom to top to be subjected to a reaction with the tin drops; the mixture is sprayed to a collection chamber on one side of the atomization chamber; chlorine is collected from the upper side of the collection chamber; liquid stannic chloride is collected from the lower side of the collection chamber. The sprayed fluid is broken under centrifugal force of the rotating roller, chlorine collides with the tin drops at a high speed and is mixed sufficiently with the tin drops to be subjected to a reaction, the reactants can be sufficiently mixed and then sprayed to the collection chamber through a sprayer, and collection of a product and chlorine is greatly facilitated. The generated stannic chloride can flow to the bottom of the atomization chamber from top to bottom under the action of gravity, sufficient reaction is realized, the quality of the product can be improved, continuous production can be realized, and the yield can be increased.