The invention relates to a multi-wavelength synchronous output fiber laser based on nonlinear polarization rotation mode locking, which comprises a semiconductor laser, a wavelength division multiplexer, a gain fiber, a first collimating mirror, a first half wave plate, a first quarter wave plate, a first polarization beam splitter, a Faraday isolator, a glaring grating, and a silver mirror. According to the first half wave plate, a nonlinear polarization rotation technology is adopted for mode locking, a saturable absorber which is likely to be damaged can be prevented from being used, and the stability of the laser is enhanced. According to the same laser gain fiber and the nonlinear polarization mode locking device, the distance between two wavelengths under mutual cross phase modulation effects in the laser cavity is increased, and thus, a cavity length misadjustment range for two laser cavities in the case of synchronous mode locking can be increased. Through changing the angle of a beam-splitting grating, the output wavelength of the laser can be tuned, the gap between the two wavelengths can be changed through changing the position of the collimator in the spectral space, and through changing the position of the collimator away from the beam-splitting grating, the pulse spectral width and the pulse width of laser output pulses can be changed.