In high power all fiber laser systems, the backward stimulated Raman Stokes light will be absorbed in combiners and converted into heat finally, which can cause damage to devices and restrain output power. Forward Raman compatible fiber laser concept is put forward to suppress the backward Raman Stokes light by injecting an auxiliary seed. The model of master oscillator power amplifier (MOPA) with stimulated Raman scattering (SRS) effect is simulated and the characteristics of backward Raman Stokes light are discussed. The effects of different auxiliary seeds injections on the increase of output power are compared. Results of simulations have illustrated that the output power of the system can be increased by more than one time when the certain power and wavelength auxiliary seed are injected.