The invention discloses metal cutting fluid containing nanometer titania of different particle sizes and a preparation method of the metal cutting fluid. The prepared metal cutting fluid has low tapping torque and is excellent in lubricating property and low in grinding spot diameter, the wear resistance of the metal cutting fluid is excellent, the maximum non-seizure load PB value is great, the extreme pressure resistance is obvious, and the antibacterial property is outstanding. The metal cutting fluid does not contain sodium nitrite or any other substance toxic and harmful to the environment, takes vegetable oil as a main ingredient, is added with some high-efficiency additives, and is green, environmental-friendly, high-efficiency, simple in formula, excellent in antibacterial propertyand difficult to deteriorate. Due to the addition of silver-loaded graphene, silver particles are loaded among graphene sheet layers, so that the dispersion property of the graphene is further enhanced, the sheet stripping is full, and the anti-wear and friction reducing properties of the prepared cutting fluid are enhanced. Meanwhile, the cutting fluid is endowed with an antibacterial effect, the cutting fluid is difficult to deteriorate, and the storage period is prolonged.