Structured illumination microscopy (SIM) is a rapidly developing a super-resolution optical microscopy technique. With SIM, the grating is needed in order to rotate several angles for illuminating the sample in different directions. Multiple rotations reduce the imaging speed and grating rotation angle errors damage the image recovery quality. We introduce mirror transformation on one-dimension (1D) Fourier spectrum to SIM for resolving the problems of low imaging speed and severe impact on image reconstruction quality by grating rotation angle errors. When mirror operation and SIM are combined, the grating is placed at an orientation for obtaining three shadow images. The three shadow images are acquired by CCD at three different phase shift for a direction of grating. Thus, the SIM imaging speed is faster and the effect on image reconstruction quality by grating rotation angle errors is greatly reduced.