Abstract:Quasar SDSS J151653.22+190048.2 (J1516+1900) presents very peculiar spectral characters in the observed ultraviolet, optical, and infrared bands: the full widths at half maximum intensity (FWHM) of optical emission lines (Hα, Hβ, and in frared Paα and Paβ) are all larger than 5000\;km/s, and the equivalent widths of these emission lines also approach to those of normal quasars; while the ultraviolet emission lines (Lyβ, OVI, Lya, NV, SiIV, and CIV) are dominated by intermediate-width emission lines (IELs) with FWHM \sim 1700\;km/s. This phenomenon can be explained as a partially obscuration effect: the broad emission lines (BELs) in ultraviolet are heavily suppressed by the dust extinction and thus the IELs become prominent; the dust extinction in optical is not significant, and the IELs are hard to be detected due to the brightness of BELs. Using the IEL width and central super-massive black hole mass M_{\rm BH} \sim 5.75 \times 10^8\;M_\odot of J1516+1900, and assuming that the intermediate-width emission line region (IELR) is virialized, we estimate the distance of IEL region to central black hole is about 1.6\;pc. On the other side, by combining the photo-ionization calculations and observed IELs intensity, we find the IELR has a density of \sim 10^{12}\;\rm cm^{-3}, ionization parameter of \sim 10^{-0.65}, and its distance to the central region of \sim 0.016\;pc, which is one percent of that based on the virialized estimation. This contradiction can provide an important clue for studying the geometry, physical condition,and the origin of emission line region in active galactic nuclei.