The invention provides a method for producing an ultrathin quartz crystal phase retardation plate with high yield and stable quality. The method sequentially comprises the following working procedures of checking raw materials, designing the shape of a crystal, orientating an angle, designing a cutting form of a crystal plate, cutting a plurality of lines, processing the shape of the crystal plate, and grinding, polishing, washing, plating, gluing, forming, detecting and packaging the crystal plate, and putting into storage. The key point is that: in the polishing working procedure, the crystal plate to be polished is glued on a substrate, and then is polished; and in the washing working procedure, the substrate is separated from the crystal plate, and then the crystal plate is washed. The single quartz crystal to be polished is glued on the substrate, so that the mechanical strength of the single quartz crystal to be polished is improved; and then the single quartz crystal to be polished is polished, so that the crystal plate has extremely high parallelism, high transmittance, high light loss resistance threshold value and high mechanical performance, is particularly stable in use occasions with a large temperature difference range, has a wide wavelength range, permits large-angle incidence (about 20 degrees), and can be applied to the use occasions with high loss threshold value (more than 1 GW/cm<2>).