Discrete optical system refers to an optical system composed of a finite number of different optical paths and discrete optical components. Therefore, the discrete optical system integrated into the optical fiber is to study how to build these discrete optical devices in a single optical fiber, how to establish correlations between each optical unit through the change of spatial structure, and through what method to change and regulate the relationship between these discrete optical devices and their light field interaction. To answer these questions, it becomes the key to realize the fiber-integrated optical field manipulation of the discrete optical system in a fiber. In this chapter, several examples of discrete waveguide fiber-integrated optical field manipulation are given: (1) the method of optical field mode transformation based on the coupling of discrete waveguide fiber is explained; (2) the technical way to realize the adaptation between different optical fields through the regulation of waveguide coupling is explained; (3) The tuning effect between the coherent phases of multi-path interference is demonstrated.