Ultrashort pulse fiber lasers have received widespread attention because they play a vital role in telecommunications, biology, and photonics. Many mode-locking technologies have been applied to construct passive mode-locking fiber lasers, such as semiconductor saturable absorption mirrors, graphene, nonlinear polarization rotation, carbon nanotubes, etc. In recent years, researchers have conducted extensive research on multimode fibers and proposed nonlinear multimode interference technology based on multimode fibers for the generation of ultrashort pulses. Compared with traditional mode-locked devices, multi-mode interference-based mode-locked devices have the advantages of high damage threshold, simple structure, adjustable wavelength and controllable modulation depth. In this study, we constructed a multimode interference mode-locked fiber laser by squeezing a piece of GIMF into the polarization controller works as SA. By introducing the dispersion management into the cavity, stretched pulse with 3 dB bandwidth of 37.2 nm was obtained. After compression, these pulses have a hundred-femtosecond duration. By carefully adjusting the PC and increasing the pump power, dispersion-managed soliton molecules was acquired, and the modulation period of spectrum is 0.32 nm. The experimental setup of the dispersion-managed all-fiber laser based on the SMS structure is depicted in Fig. 1. A 0.8 m long piece of single-mode HEDF was utilized as the gain medium, which was pumped by two 980 nm LDs through 980/1 550 nm WDM. Unidirectional operation was ensured by polarization independent optical isolator. The SA based on the SMS structure in the cavity was used as a mode-locking device, in which a 0.153 m long piece of GIMF was squeezed in the PC and the polarization states of the light in the multimode fiber was changed by tuning the PC. The net cavity dispersion can be managed by using a segment of DCF. In the experiment, the length of DCF is 0.3 m. The GVDs of HEDF, SMF, and DCF at 1.5 μm are 15.7, 18, and -?152.6 ps/nm·km, respectively. Due to the short length of the GIMF, the dispersion effect of the GIMF was neglected. Thus, the total net cavity dispersion is calculated to be -?0.105 09 ps², and the laser operated in negative dispersion region. Considering the pigtails of all intracavity devices, the cavity length is 7.4 m, corresponding to the fundamental repetition frequency of 27.02 MHz. A 10∶90 OC was employed to collect 10% power from the cavity. A compressed structure was built to acquire the minimum pulse width. In order to avoid the splitting and distortion of the pulse caused by the excessive peak power during the power amplification process, a section of DCF was welded between the PC and the amplifier to stretch the pulse in advance. As the gain medium of the amplifying structure, the EDF with normal dispersion at 1 550 nm was also used as a part of dispersion compensation. The dispersion caused by the amplifier further reduced the chirp of the pulse. When the pump 1 and pump 2 increased to 95.1 mW and 350 mW, self-starting dispersion-managed mode-locked pulse can be observed by appropriately rotating and squeezing the GIMF inside the PC. Figure 3 shows the features of the SP with pump 1 and pump 2 power of 95.1 mW and 750 mW. As the pump power increased, the spectral bandwidth and output power became wider and bigger and arrived its maximum of 37.2 nm and 1.7 mW respectively. Optimizing the length of DCF can compress the pulse from 973.2 fs to 280.1fs with the compressed structure after the output port of cavity. When the pump 2 increased to 856 mW, the pulses form stable soliton molecules by carefully adjusting the PC. The pulse width of a single dispersion-managed soliton molecules is 4.04 ps, and the pulse interval is 24.1 ps, which corresponds to the 0.32 nm spectral modulation period. The output characteristics of stretched pulses and dispersion-managed soliton molecules in dispersion-managed multimode interference mode-locked fiber lasers are studied. The output of the mode-locked pulse is realized by squeezing the graded index multimode fiber into the polarization controller. When the total pump power is 845.1 mW, a stretched pulse with a central wavelength of 1 528 nm, a 3 dB bandwidth of 37.2 nm and a pulse width of 973.2 fs is obtained by carefully adjusting the PC. A compressor is built to acquire the minimum pulse width and the DCF is used for dispersion compensation to compress the pulse width of the stretched pulse to 280.1 fs. By further increasing the total pump power to 951.1 mW and adjusting the PC, the soliton molecules are obtained, and the modulation period of the dispersion-managed soliton molecules is 0.32 nm, corresponding to pulse interval of 24.1 ps. This phenomenon provides a reference for the research on multimode interference fiber lasers.