Abstract: The standard white field instrument traceable to the national spectral radiometric, photometric and colorimetric primary standard was set up forcharacterizing the photometric and colorimetric parameters of displays. The instrument was calibrated and its spectrum, stability and photometric-colorimetric parameters were given. Using the instrument to study the viewing angle of prevail liquid crystal displays, the influence of the variation of the light-emitting surface during the measurement process was considered, which was usually ignored. The results indicate a difference of more than 8% for the absolute-luminance-based viewing-angle threshold method, which should be considered and avoided in the measurement.