Driven by the demand of science and technology, synchrotron radiation (SR) facilities continue to develop. At present, the development of SR has gone through three generations, and is in the vigorous development stage of the fourth generation (4^th). SR based on diffraction-limited storage ring is one of the typical representative of the 4^th synchrotron light sources. The mainstream of the 4^th SR is to further reduce the electron beam emittance, so that the light source from the 4^th SR exhibits excellent transversal coherence and is able to produce circular cross-section radiation. If the beam emittance drops to the optical diffraction limited “radiation wavelength/4π”, its brightness enhances to 2-3 orders of magnitude higher than that of the third generation SR light source. The qualitative leap in the performance of this SR light source will bring a substantive breakthrough to the SR-based experimental techniques, and bring new opportunities to the cutting-edge scientific and technological research, as well as the development of modern industry. Starting with the development trend of worldwide SR facilities, this review first introduces the characteristics and performance of low-energy diffraction limited storage ring (DLSR) light source, then introduces the progress of experimental techniques brought by DLSR, and illustrates the application of low-energy DLSR light source in material science, energy science, life science and environmental science, as well as its industrial opportunities. Finally, the technical breakthrough and potential application prospect of low energy DLSR light source are summarized and prospected.