We report that the phase of a backward wave by stimulated Brillouin scattering (SBS) can be controlled by a self-generated density modulation without any backward Stokes seed beam, which is generated due to electrostriction induced by electromagnetic standing wave through the interferences between the main beam and the low intensity counter-propagating beam. The density modulation ignites the position of the Brillouin grating so that the phase of the backward SBS can be controlled. We obtained 96% success with the phase error less than a quarter wave under a proper scheme of the self-seeding methods. This phase control technique is so simple, scalable, and very efficient that it can be applied to many beam combination systems for a high power laser system with a high repetition rate over 10 Hz. (C) 2005 American Institute of Physics.