We report some results of theoretical analysis and experimental study of selective properties of 3D holographic grating. In particular, the case of strong deviation of the propagation vector of the reconstructing wave from Bragg conditions by tuning the wavelength and/or the angle of the incident illuminating beam is considered. In this case, it is more convenient, to operate with joint function of angular-spectral selectivity. The character of this joint function should be taken into consideration, if true color holographic images are of interest. Key words: angular and spectral selectivity, 3D reflection grating, diffraction efficiency.