The invention relates to a mode locking pulse optical fiber laser based on an SMS structure. The mode locking pulse optical fiber laser comprises a pumping source, a wavelength division multiplexer, apolarization single-mode-multimode-single-mode structure, an output coupler, a gain optical fiber and a polarization independent isolator, wherein the pumping source is connected with the wavelengthdivision multiplexer; the wavelength division multiplexer is connected with the polarization single-mode-multimode-single-mode structure; the polarization single-mode-multimode-single-mode structure is connected with the output coupler; the output coupler is connected with the gain optical fiber; the gain optical fiber is connected with the polarization independent isolator; the polarization independent isolator is connected with the wavelength division multiplexer; and the wavelength division multiplexer, the polarization single-mode-multimode-single-mode structure, the output coupler, the gain optical fiber and the polarization independent isolator are sequentially connected to form an optical fiber ring cavity structure. The mode locking pulse optical fiber laser achieves full optical fiber mode locking in a SMS structure and polarization controller combined manner; manufacturing of a mode locking structure and a mode locking device is simplified; and compared with the traditional mode locking optical fiber laser, the mode locking pulse optical fiber laser is simpler and more compact in structure and higher in damage threshold.