The invention discloses a method for preparing large-size molybdenum plates for sputtering targets of liquid crystal display (LCD) flat-panel displays, which comprises: 1), uniformly brushing an antioxidation coating on the surface of a molybdenum plate blank by pressing and sintering by the conventional process; 2), covering the molybdenum plate blank with the antioxidation coating with a steel capsule; 3), rolling the molybdenum plate blank covered with the steel capsule by one time of heating, and cooling the rolled molybdenum plate blank on a cold bed; 4), rolling the cooled molybdenum plate blank till the thickness (including the steel capsule) of the molybdenum plate blank is between 19 and 24 millimeters; 5), leveling the rolled molybdenum plate blank, removing the steel capsule, cutting the molybdenum plate blank and obtaining semi-finished molybdenum plates; and VI, performing the vacuum heat treatment of the semi-finished molybdenum plates, and obtaining the large-size molybdenum plates for the sputtering targets of the LCD flat-panel display. The large-size molybdenum plates for the sputtering targets of the LCD flat-panel display, which are prepared by the method of the invention, have flat surfaces, the density of the plates is more than or equal to 10.15g/cm<3>, the microscopic structure of the plates is uniform equiaxial structure, and the average grain size of the plates is not more than 200 mu m.