A simple scheme using fiber Bragg gratings to realize dual-wavelength optical auto gain clamping erbium-doped fiber amplifier is proposed and demonstrated. It shows that in three kinds of different clamping wavelength combinations: 1535.64 nm and 1562.68 nm,1530.48 nm and 1562.68 nm,1530.48 nm and 1551.36 nm,the outputs gain and dynamic state scopes of 1540 nm signal are almost the same. For above three clamping wavelength combinations,loop loss is 14.7 dB,15 dB and 15 dB,respectively. For the same pump conditions and loop loss,these three kinds of clamping wavelength combinations lead to almost the same results,which is proved by experimental results. However,the result is very different from above under the condition of 1551.36 nm and 1562.68 nm clamping wavelength combinations. It is revealed that when designing a dual-wavelength optical auto gain clamping EDFA,to get high gain,the separation of two clamping wavelengths should be as big as possible.