The invention relates to a preparation method of a modified polycarbonate material for 3D printing. The method comprises the following steps: weighing, by weight, 100 parts of polycarbonate, 0-10 parts of a thermotropic liquid crystal polymer, 10-25 parts of polycaprolactone, 8-15 parts of a toughening agent, 0-2 parts of hydrophobic fumed silica, 0.2-0.5 part of a hindered phenolic antioxidant and 0.2-0.5 part of a phosphite antioxidant, mixing above raw materials, adding the obtained mixture into a twin-screw extruder, performing extruding granulation, drying obtained pellets, adding the dried pellets into a single-screw extruder, performing extrusion to obtain a plastic melt, and performing hot water treatment, cold water cooling setting and air drying on the plastic melt to obtain a wire. The method is convenient and economical, and is suitable for mass production, the prepared modified polycarbonate material for 3D printing has the advantages of realization of printing at a temperature of 260 DEG C or less, high tensile strength, high notched impact strength, and no thermal degradation, and products printed by using the material do not warp and have a smooth surface.