Recently, the UV gold-enhanced reflectance coating for a collimating mirror, which has an aperture of Φ516mm, in LAMOST spectrometer has been successfully achieved by researchers of Nanjing Institute of Astronomical Optics & Technology, National Astronomical Observatories, CAS. The surface precision has no significant changes before and after coating. The PV and RMS are 0.25303λ and 0.0197λ before coating, and 0.30692λ and 0.0196λ after coating, respectively. The average reflectance in the working band is above 98%. The gold-enhanced reflector compensates for the defects of aluminum and silver film performance, and has the characteristics of wide bandwidth, high efficiency, low stress and long service life. The successfully coating of the collimator mirror marks the fact that this film system has been applied to astronomical telescopes.