A fabrication method of a trench metal oxide-semiconductor (MOS) transistor is provided. After the gate trenches are formed in the epitaxial layer, impurities of a first conductive type are implanted into the epitaxial layer by using a blanket implantation process. A polysilicon pattern filling the gate trenches and covering a predetermined range of epitaxial layer surrounding the gate trenches is formed on the epitaxial layer. Impurities of a second conductive type are implanted through the polysilicon pattern into the epitaxial layer to form a well. Impurities of the first conductive type are implanted to form a plurality of first doping regions. A portion of the polysilicon layer above the upper surface of the epitaxial layer is removed by etching to form a plurality of polysilicon gates. Impurities in the first doping regions are driven in to form a plurality of source regions adjacent to the gate trenches.