The invention provides a preparation method of weighted drilling fluid, wherein, a plurality of pieces of milling equipment are added during the preparation of the weighted drilling fluid on the basis of the conventional processes of stirring and mixing as well as liquid flow shearing, and the series connection, parallel connection or the combination of both is adopted, namely to add a milling procedure. Furthermore, a milling method and the conventional stirring and mixing method, or the milling method and the conventional liquid flow shearing method, are mutually combined to prepare the weighted drilling fluid. The milling equipment comprises any machine product that is provided with the structure of flexible and static cutting discs or a stator and a rotor and generates the milling function by relative motion, such as a colloid mill, an asphalt colloid mill, a food paste mill, etc. By adopting the milling method, the weighted drilling fluid prepared can be not only applied to the laboratory evaluation, but also applied to the factory-like production or the on-site petroleum drilling; the maximum density of the prepared drilling fluid can be up to 3.0 g/cm<3>.