LAMOST(Large sky Area Multi-Object fiber Spectroscopic Telescope)is a Chinese national scientific research facility operated by National Astronomical Observatories,Chinese Academy of Sciences(NAOC).After two years of commissioning beginning in 2009,the telescope,instruments,software systems and operations are nearly ready to begin the main science survey.Through a spectral survey of millions of objects in much of the northern sky,LAMOST will enable research in a number of contemporary cutting edge topics in astrophysics,such as discovery of the first generation stars in the Galaxy,pinning down the formation and evolution history of galaxies-especially the Milky Way and its central massive black hole,and looking for signatures of the distribution of dark matter and possible sub-structures in the Milky Way halo.To maximize the scientific potential of the facility,wide national participation and international collaboration have been emphasized.The survey has two major components:the LAMOST ExtraGAlactic Survey(LEGAS)and the LAMOST Experiment for Galactic Understanding and Exploration(LEGUE).Until LAMOST reaches its full capability,the LEGUE portion of the survey will use the available observing time,starting in 2012.An overview of the LAMOST project and the survey that will be carried out in the next five to six years is presented in this paper.The science plan for the whole LEGUE survey,instrumental specifications,site conditions,and the descriptions of the current on-going pilot survey,including its footprints and target selection algorithm,will be presented as separate papers in this volume.