In this work, we propose and demonstrate a dual-reflected-structure erbium-doped fiber (EDF) laser with a linear cavity using a passive saturable-absorbor-based (SAB) filter to achieve single-longitudinal-mode (SLM) lasing. Here, we can observe the wavelength tuning range between 1530.0 and 1562.0 nm with the output powers of -13.7 to -7.6 dBm and optical signal to noise ratios (OSNRs) of 35.4 and 47.9 dB/0.05 nm, respectively. Moreover, when the lasing wavelength is tuned to the longer wavelength gradually, the obtained output power and SNR increase. This is because the Er + gain can be suppressed and moves to the longer wavelength via the proposed fiber laser structure. In addition, the output stability of the proposed laser has also been analyzed and studied.