Salt model building is a key process for successful subsalt imaging. In complex areas, Reverse Time Migration (RTM) provides better images than One-way Wave Equation Migration (OWEM) or Kirchhoff Migration (KMIG). With a superior image, RTM can give improved solutions for delineation of salt geometry. The main obstacle in applying RTM to iterative salt model building is that RTM requires substantially more computing power than OWEM or KMIG. However, the cost of RTM can be reduced by localizing the imaging area. First, perform the redatuming of source and receiver wavefields to a certain depth just above the interested subsalt target area. Second, localize the image zone near the steep salt boundary. After then, update salt geometry iteratively using localized RTM (LRTM) images and an interactive salt modeling tool.