A simple erbium doped fiber laser configuration for achieving stable dual wavelength oscillation at room temperature is proposed. In this configuration, a fiber Bragg grating written in a polarisation maintaining fiber as the wavelength selective component is used. Stable dual wavelength oscillation with a wave spacing of 0.52nm at room temperature can be achieved through adjusting the state of polarization controller. An amplitude variation within 16 scans time is less than 0.2dB for both wavelengths.