Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) is a quasi-meridian reflecting Schmidt telescope with an effective light-collecting aperture of 3.6 m to 4.9 m (depending on pointing direction) and a 5∘ field of view in diameter (Wang et al. 1996; Su & Cui 2004; Cui et al. 2012), located in Xinglong Station of National Astronomical Observatory, China (NAOC). It has 4000 robotic fibers, with 3.3 arcsec diameter, mounted on its focal plane and connected to 16 spectrographs. Each spectrum of the target is split into two channels, red and blue, and then recorded on red and blue cameras, respectively. The blue channel is optimized for 3700–5900 Å, and the red channel for 5700–9000 Å, with 200 Å overlaps between the two channels. The spectral resolution reaches R∼1800 over the entire wavelength range (see Cui et al. 2012). LAMOST regular survey, carried out from September 2012, was designed to have two major components: the LAMOST ExtraGAlactic Survey (LEGAS) and the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) survey of Milky Way stellar structure (Zhao et al. 2012). The LAMOST quasar survey was conducted under LEGAS, which covers the high Galactic latitude area in the northern sky. This survey aims to make census of quasars at different redshifts for better understanding the growth of supermassive black holes and the co-evolution with their host galaxies.