The method to realize a beacon of small area on an uncooperative and extended target by using stimulated Brillouin scattering (SBS) threshold effect is presented. The process of laser propagation through 10km atmospheric path with SBS is simulated in cases of different atmospheric turbulence (C 2 n=10 -16 ～10 -12 ). The distribution of the phase conjugate light on the target was obtained from the simulation. The experiments of laser propagation with SBS are made in cases of different environments. The maximum distance is 250 m. The results indicate the laser propagation with SBS effect and the method to realize the beacon of small area on the target are feasible.