The 7-Dimensional Telescope(7DT) is a multiple telescope system for observing the Universe in an unprecedented way, which is composed of twenty 0.5m wide-field telescopes. It is being constructed in Chile, with a target completion date of 2023. “7-Dimension” in its name represents the 7-dimensional space of the Universe that we will explore in the x, y position (2D), the distance (2D), the radial velocity (1D), the brightness of the objects (1D) in the sky to be measured along the wavelength (1D) and the time (1D). Therefore, the 7DT will obtain the spectral movie of the Universe for the first time. The 7DT is expected to make significant contributions to the newly-born “multi-messenger astronomy” by identifying the electromagnetic counterparts of the gravitational-wave sources. The 7DT will perform a survey called the 7-Dimensional Sky Survey (7DS), which is expected to tackle difficult problems in many fields of astronomy ranging from cosmology. galaxy evolution, supermassive black holes, tidal disruption of stars, solar system objects, supernovae and transients, and the star formation in our galaxy.