This paper discusses the technique of the spectral beam combing (SBC) in the solid-state lasers, including the fiber laser, the Yb:YAG slab laser, and the diode laser. For the fiber lasers, we study the beam quality degeneration (BQD) in SBC due to the dispersion of three kinds of diffraction optics elements (DOE): single multi-layer dielectric (MLD) grating, a couple of MLD gratings and multiple volume Bragg gratings (VBG). We point out that, for all cases, BQD is determined by the full-width of the second-order moments instead of the full-width of half maximum in the spectrum of sub-beams. But the value of BQD depends on the DOEs. For solid-state crystal lasers, we demonstrate the feasibility of SBC in the Yb:YAG slab laser by designing an experiment for an intra-cavity SBC employing an MLD grating. The experiment results SBC of seven sub-beams and 241 W laser output, the beam quality after SBC is β≈4.1. It indicates that the output power of the Yb:YAG slab laser can be further scaled by SBC. Finally, we demonstrate a new technique to scale the output power of the laser diodes (LD), which includes the large modal external oscillation in the slow-axis and the SBC in the fast-axis simultaneously. The experiment results the SBC of nine LDs with the slow-axis width of 1 mm, the beam qualities after SBC are β≈6.3 in the slow-axis and β≈1.6 in the fast-axis. It means that beam quality after the SBC in the fast-axis is controllable.