Provided are a dental implant with a nano bacteriostatic structure ring at a transgingival part and a machining method thereof. The transgingival part of the dental implant has a three-level micro-nano composite structure, and the three-level micro-nano composite structure endows a surface of the transgingival part of the implant with functions of promoting adhesion and proliferation of a gingival fibroblast and a gingival mesenchymal stem cell and inhibiting adhesion and growth of various oral bacteria. A preparation method thereof comprises: firstly, injecting bioactive, wear-resistant or corrosion-resistant C, N, Ca and P elements into the transgingival part of the dental implant by a plasma injection method; and then, preparing the three-level micro-nano composite structure at a part in which the elements are injected.