In this paper, the in-plane spectral bidirectional reflectance distribution function(BRDF) of red copper surfaces in the waveband of visible light was measured using a self-developed measuring device. The influences of wavelength, incident zenith angle and surface roughness on the measurement results were analyzed in detail. The results show that the BRDF curve versus wavelength is mainly affected by the color of the sample surface and is not affected by the incident and reflected angle; the incident zenith angle has obvious influence on the measurement results, which can be attributed to angle factor and the change of reflectance intensity varying with incident zenith; and roughness has a significant impact on the measurement results. With an increase of roughness, the reflection near the mirror′s direction is weakened, while the reflection in the other directions is strengthened. In addition, Gauss and Lorentz distribution functions are used to fit the measurement data and the fitting results are incoordance with Lorentz distribution.