A simple wavelength tunable erbium doped fiber laser, with a fiber polarization controller and a polarization dependent isolator (PDI) as wavelength selective devices, is theoretically and experimentally demonstrated, which consists of gain flattened erbium doped fiber amplifier (EDFA), polarization dependent isolator, fiber polarization controller, and output coupler. The polarization induced losses of different wavelengths were analyzed with Jones matrix; theoretical result showed that wavelength-tunability and dual-wavelength operation of the fiber laser could be obtained by adjusting the polarization controller. A tunable range from 1542 nm to 1564 nm, the side-mode suppression ratio above 35 dB and average output power over 2.6 mW were achieved for this fiber laser. Dual-wavelength operation at 1549 nm and 1564 nm of the fiber laser was also obtained.