The invention belongs to the technical field of high polymer materials, and discloses high-transparent polysulfone resin and a preparation method thereof. The preparation method particularly comprises the steps of a salt-forming reaction, a polymerization reaction and post-treatment. A cycloparaffin bisphenol compound is added in the polymerization reaction, the regularity of a polymer chain is destroyed, the degree of crystallinity is decreased, the hydroxy end-capping high-transparent polysulfone resin is prepared, original excellent properties of polysulfone are reserved, the high-transparent advantage is achieved, and better application prospect and great market value are achieved. By controlling the solid content of a system and adopting specific solvent and high-pressure polymerization, the time of the polymerization reaction is greatly shortened, the energy consumption is reduced, a water separation agent does not need to be added, and the post-treatment processes are reduced.