A new spectral beam combination scheme based on cascaded volume Bragg gratings (VBG) was presented. The number of beams can be multipled with the number of cascaded gratings. A system as example based on two cacaded VBGs was given. All the beams were firstly divided into two groups according to their wavelength. Each group was then combined by a VBG with corresponding central wavelength. Because the angular selectivity of the two VBGs are not overlapped, all the beams can be steered to propagate in the direction of the Bragg angle of the second VBG. The power of all beams can then be added at the near and far fields. In order to assure the consistency of the propagating direction of all beams, a formula to accurately determine the incident angle of all beams was derived using rigorous coupled-wave theory. Numerical results show that the average diffraction efficiencies of all beams are higher than 80%, and the deviation of the propagating direction of all diffracted beams are less than 4×10-7 rad when the incident angle of all beams deviates from their theoretical value less than ±5′.