A simple self-seeding scheme was demonstrated for tunable dual-wavelength optical short pulse generation with enhanced sidemode suppression ratio. The two wavelengths and their separation can be tuned in a flexible manner by adjusting two fiber Bragg gratings and an optical delay line. The sidemode suppression ratio of the output pulses achieved is close to or better than 30 dB over the wavelength-tuning range of 20.7 nm. The system is simple and robust and convenient for dual-wavelength tuning.