This paper reviews the research status of the mechanism and technology of all-fiber mode-locked laser ultrashort pulses and bound state soliton generation based on graded index multimode fiber saturable absorber. Using this noval type of all-fiber structured mode-locking modulation device， the output the single pulse energy of conventional soliton in fiber laser can up to the order of nJ， meanwhile spatial mode-locking operation can be realized. As the all-fiber nonlinear saturable absorber， the graded index multimode fiber has important research significance and wide application in lasers， and provides an important technical approach for the generation of higher energy ultrashort pulses.