A metal oxide/silicon dioxide-coated quantum dot and a preparation method thereof are provided. The metal oxide/silicon dioxide is selected from aluminum oxide/silicon dioxide, zirconium dioxide/silicon dioxide, titanium dioxide/silicon dioxide or zinc oxide/silicon dioxide, and the content of the metal oxide/silicon dioxide in the metal oxide/silicon dioxide-coated quantum dot is 1 wt % to 98 wt %. The metal oxide/silicon dioxide-coated quantum dot is prepared by one of a sol-gel method and a pyrolysis method.