Complex optical fields usually refer to structured light fields with special distributions of phase, amplitude, polarization and so on, including vortex light fields represented by orbital angular momentum patterns and vector light fields with non-uniformly distributed polarization states. The construction of a multi-dimensional multiplexing optical fiber communication system using complex optical fields has become a research hotspot of the space division multiplexing optical communication technology. The methods of generation, regulation and transmittance of a complex light field through an optical fiber are introduced. In addition, the application of a new ring core fiber in the low complexity short-distance mode multiplexed optical fiber communication system is introduced. The experiment on the Q-plate-based short-distance direct detection vector mode multiplexed optical fiber communication system is introduced. The fiber grating coupled mode conversion method as well as the generation of the first-order and second-order orbital angular momentum modes using a few-mode fiber is briefly analyzed. At the same time, the technical scheme for measuring the characteristics of a vortex light field by one-dimensional and two-dimensional periodic gradient phase gratings is introduced. The fiber loss and mode crosstalk are the key factors limiting the performances of a mode-multiplexed fiber communication system based on complex optical fields. Thus, it is still a great challenge to generate and control a high-order complex optical field based on an optical fiber. However, complex light field mode multiplexing technology as a multiplexing technology based on optical fiber eigenmodes, its related researches have important research significance and potential application value in the future super-capacity mode multiplexed optical fiber communication system.