Multimode fiber has attracted the interest of researchers for its special research value and application in the fields of optical solitons,spatiotemporal mode-locking,high-energy fiber laser,ultra-fast fiber laser and high-energy laser transmission,etc.This paper summarizes the research progress of multimode optical fiber devices,analyzes the current status and existing problems of mode-locking lasers,new mode-locking devices and nonlinear self-cleaning effect based on multimode fiber,and discusses also its future development direction.