A widely tunable multiwavelength Brillouin/erbium fiber source is experimentally demonstrated. The Brillouin Stokes signals return back to the linear cavity owing to the effect of stimulated Brillouin scattering. The influence of the self-lasing modes is effectively eliminated because of the weak reflectivity. The tuning range of the fiber source is only limited by the bandwidth of erbium-doped fiber amplifier and the tuning range of Brillouin pump signal. The pump threshold of Brillouin gain is effectively reduced by the double-pass Brillouin pump signal amplification. The fiber source provides a tuning range of 40 nm (1530～1570 nm). At the Brillouin pump power of 2 mW and the 1480 nm pump power of 110 mW, 5 output channels with 0.084 nm channel spacing from 1540 to 1566 nm are achieved.