Spectral beam combining (SBC) is a method of combining multiple laser beams of different wavelengths to achieve high-power laser. According to the current research status of SBC with external cavity for semiconductor lasers, the research progress of various schemes by using non-off-axis and off-axis approaches is reviewed firstly, and then the design ideas of different methods are summarized. Further, the advantages of each scheme for raising power and beam quality of combined laser beam are analyzed, and the possible development trends in the future is prospected for improving beam performance.