In order to obtain the detailed distribution information of background radial brightness, the measuring method of ground-based whole sky background radiance spectra is developed based on the fiber optical spectrometer and two-dimensional turntable. It can realize the fixed point observation and scanning all the sky. Structure of system, scheme of data detection, principle and method of calibration are introduced in detail. After one scanning, 649 samples of radiance can be obtained. Spectral resolution of each sample is 0.5 nm. Measuring position of each sample is used as pixel and each wavelength radiance of the position is used as gray level. The distribution of whole sky background radiation spectrum band is obtained. The proposed method provides more detailed information for further scientific research.