The present application is applicable to laser technology field and provides a dual-wavelength synchronous pulsed fiber laser based on rare earth ions co-doped fiber, which includes a continuous light LD pumping source, a rare earth ions co-doped fiber and two resonant cavities. Sensitizing ions in the rare earth ions co-doped fiber absorb the pumping light and radiate laser of one wavelength. Meanwhile, sensitized ions in the rare earth ions co-doped fiber radiate laser of another wavelength. Laser generated by sensitizing ions is subjected to Q-switching or mode locking with the saturable absorber inserted in the cavity to generate pulsed laser. Generation and partial reabsorption for the pulsed laser modulates gain of the laser radiated by sensitized ions periodically and generates synchronous pulsed laser, thereby implementing a dual-wavelength synchronous pulsed fiber laser.