A section of G. 652 fiber was spliced into the Yb-doped ring fiber laser as multimode fiber for lasing light. This combination of fiber types acts as a wavelength-dependent dynamical comb-like filter in the laser through spatial mode beating. Up to six stable laser wavelengths can be obtained in the region of 1030 nm with spectrum linewidth of 0. 15 nm and SMSR of 40 dB. By adjusting the polarization state of the light, the number of lasing wavelength and its space can be controlled.