Relying on the nonlinear multimode interference in multimode fibers and the nonlinear polarization rotation, these two mode-locked techniques are combined in our proposed fiber laser. Stable optical soliton and multi-pulse regimes with a constant frequency of 11.44 MHz have been generated experimentally. Through altering intra-cavity conditions, bound-state pulses with diverse properties are observed. To the best of our knowledge, the obtained bound-state pulse constituted by more than thirty sub-pulses is achieved for the first time. Moreover, the center wavelength of bound-state pulse could be switched in a certain range covering the entire C band.