Injecting light from laser diode (LD) into fiber is the precondition of researching fiber optical laser and fiber optical amplifier. Single-tube diode, LD bar, LD two-dimensional stack and LD array all belong to LD, their coupling technologies are different and related. This paper introduces and analyzes the representative LD tube’s coupling technology such as cylindrical wedge method, V-groove method, micro-lens method; LD bar’s coupling technology such as optical fiber bundle coupling method, beam shaping method; and coupling technology of LD 2D stack and LD array with optical fiber. The common points of these methods are compared for the choice and reference of future researchers.