The invention discloses a preparation method for a quantum dot possessing at least a four component core/shell/oxide outermost casing structure, a quantum dot prepared by the method, and the application of the quantum dot. The present process of manufacturing a quantum dot has a fast response speed, is difficult, needs consuming a lot of process equipment and time in synthesizing a core and a shell, and is low in volume production. The preparation method of the invention comprises the steps of: a) reacting in a precursor solution selected from 11 to 17 groups of elements to form at least a four component core and a core structure formed on the surface of the core; and b) mixing with the precursor solution having a nanocrystalline metal oxide or a semiconductor oxide dissolve therein, and reacting the mixed solution with a basic hydroxide solution to form a metallic oxide or semiconductor oxide to be used as an outmost structure. The core of the quantum dot at least possesses four components, is not limited by response temperatures and time in synthesis compared with a two component core, and is suitable for volume production.