An application-oriented spaceborne radar advanced simulator (SBRAS) is presented in this paper. SBRAS is initiated by the technical and economical requirements to verify formation-flying distributed satellites synthetic aperture radar (SAR) scheme and simplify the instrument hardware design. The simulator develops a full flow of signal processing including formation design, SAR raw data simulation of nature scene, imaging, InSAR processing, digital elevation model (DEM) generation and performance analysis. A user-friendly GUI is provided.