The invention relates to a laser light source of diffractive optical element coherent synthesis based on active optical feedback of a ring cavity. The laser light source mainly comprises an all-optical-feedback type passive annular cavity and a two-stage active control optical loop with different tuning ranges. The laser light source is characterized in that multi-path narrow-linewidth fiber laserdevices are combined into one beam of high-energy laser for output by means of all-optical feedback common-aperture coherent synthesis; after adding of an active control type feedback loop, the initial main oscillation seed wavelength is ensured to be consistent with the central wavelength of a feedback cavity mode, so that the output line width of the synthetic laser is further narrowed, the phase noises are reduced, the interference on the ring cavity by the external environment is reduced, and the phase locking effect is stabilized. According to the invention, defects of low synthesis efficiency, strong phase noises and poor phase locking effect of the traditional passive coherent synthesis system are overcome; the high stability and safety of the synthetic system are kept; the scale of the array is extended; and the brightness of the narrow-linewidth output laser is enhanced. An effective technical path is provided for realizing high-power and good-beam-quality expansion of the fiber laser device.