Based on the coupled wave equations of nonlinear optics, a two-dimensional p hysics model is established to describe transverse stimulated Brilluoin satteri ng (TSBS) in large-aperture optics of a high-power laser system. The temporal and spatial profile of the stress induced by TSBS is evaluated numerically, and the damage characteristics of optical components is presented, which agrees well with the experimental phenomenon observed at LLN laboratory. The energy loss induced by TSBS are calculated to be up to 20%, sho wing that TSBS may have strong influence on routine operation of high-power las er systems.