Imaging a volumetric sample in real time is required to directly observe biological anatomy and mechanisms. There are a variety of microscopic imaging systems, developed to achieve optical sectioning, such as confocal microscopy. However, the drawbacks of existing systems are long scanning time or strong laser power. To overcome such problems and to obtain high-speed optical sectioning images, we demonstrate HiLo structured illumination microscopy by the use of digital micro-mirror device (DMD) and the focal tunable lens (FTL). The proposed system is configured such that hybrid uniform and non-uniform pattern are projected onto DMD to reconstruct optical sectioning images. In addition, FTL is utilized to digitally change observation plane with constant magnification and resolution; thus, mechanical movement is eliminated. Furthermore, in vivo three-dimensional (3D) images of biological samples, including a live Canenorhabditis elegans, are experimentally demonstrated.