The invention relates to a high-speed structure illumination optical microscope system and a method based on a digital micromirror device. The high-speed structure illumination optical microscope system comprises an illumination light source, a light splitting prism, a structure light generator, a lens, a spectroscope, a microobjective, an objective table, a reflector, a tubular mirror and a charge coupled device (CCD) camera, wherein the light splitting prism is arranged on a light path of the illumination light source, the structure light generator is arranged on a reflection light path of the light splitting prism, the lens is arranged on a transmission light path of the light splitting prism, the spectroscope is arranged on a lens light path, the microobjective and the objective table are arranged on a light path above the tubular mirror, the reflector and the tubular mirror are arranged on a light path under the spectroscope, and the CCD camera is arranged behind the tubular mirror. The system and the method aim at the technical problems of low optical energy utilization rate and low speed of the existing structure illumination microscope and have the advantages that the image refreshing speed is high (32KHz), and the optical energy utilization rate is high (higher than 90 percent). The system and the method are more applicable to the real-time three-dimension image study and high-speed dynamic process observation of living biological cells.