In Brillouin optical time domain reflectometer (BOTDR) system, the Brillouin scattering signal is so weak that the sensing distance is usually limited and thus the signal to noise ratio and measurerent precision are influenced in system. Therefore, the forward and backward Raman amplification of Brillouin scattering signal in BOTDR system is studied. The experimental results show that the stimulated Brillouin scattering (SBS) threshold by the backward pump Raman amplification is higher than that by the forward pump Raman amplification. When the pump power is 700 mW, the gain of the forward pump is about 13.78 dB, then the amplified gain will decrease because of the occurence of the second order Brillouin scattering spectral line. When the pump power is 1000 mW, the gain of the backward pump is about 16.33 dB, and it still has the growth trend subsequently, which is beneficial to the continuous amplification of the Brillouin backscattering signal.