In order to realize wavelength tunability of mode-locked fiber laser, a passively mode-locked ytterbium-doped fiber laser with ring cavity was constructed with a semiconductor saturable absorber mirror (SESAM). Without any polarization controllers and tunable filters in the cavity, by changing the distance between the end face of the optical fiber jumper and the SESAM, the stable tunability of the spectrum was achieved between 1029.5nm and 1042.7nm. The fundamental frequency repetition rate was 18.0MHz, the pulse width was 130ps, and the signal-to-noise ratio of mode-locked pulse was 44dB. The results show that, the mode-locked fiber laser has a high signal-to-noise ratio and a wide tunable range. This study provides an important reference for the development of tunable passively mode-locked fiber lasers.