:Latest development of study and application on super - luminescent diode(SLD)were reviewed. The effect of the structures included active area ,rear absorption area as well as antireflection filmof light emitting facet on the spectral characteristics were analyzed. Temperature control of SLD ,alignment of the chip to pigtail and module packaging were described respectively. The requirements of Interference fiber optical gyroscope ( IFOG) ,optical time domain reflectometer (OTDR) , biomedicine optical coherence tomography(OCT) ,and Wavelength division multiplexing(WDM) for SLD were introduced respectively.