Abstract: Based upon the electromagnetic treatment, Stimulated Brillouin scattering (SBS) in a strain dependent n-InSb crystal which is subjected to a transverse magnetic field is investigated analytically. The origin of this nonlinear interaction is considered to be found in the third-order nonlinear optical susceptibility arising due to nonlinear current density and strain dependent polarization of the medium. The threshold condition is obtained for onset of the SBS process. The effective Brillouin susceptibility and gain is determined using coupled mode scheme of interacting waves. The effects of magnetic field and doping on threshold and SBS gain are studied. Numerical estimations are made at 77K duly shined by a pulsed 10.6 μm CO2 laser. In the highly doped regime the transverse magnetic filed effects a significantly decrease in the threshold and an appreciable enhancement in the SBS gain is obtained. When cyclotron frequency is nearly equal to the applied field frequency minimum threshold and maximum gain of SBS process is achieved. The numerical value of third-order nonlinear optical susceptibility by our analysis is well agreed with previously obtained theoretical as well as experimental values.