Abstract: A method for preparing a super junction trench MOSFET, comprising: providing a substrate, and forming a first trench in the substrate; depositing an epitaxial portion of a first stage in the first trench while supplying a doped gas and an etching gas, and performing an epitaxial process after stopping supplying the doped gas and the etching gas, wherein impurities in the epitaxial portion of the first stage are diffused to an upper portion of the first trench and to form an epitaxial portion of a second stage with a gradient concentration by utilizing a high-temperature environment of the epitaxial process; forming a well region, a trench gate, and an active region in the substrate at a periphery of the first trench; forming an interlayer dielectric layer covering the column, the trench gate, and the active region; and electrically leading out the column, the trench gate, and the active region.