The invention provides an SAR system based on a frequency modulated continuous wave (FMCW) system, comprising a transceiving antenna, a radio frequency module, a digital module and an image processingmodule, the radio frequency module is connected to the transceiving antenna and comprises a transmitting channel, a receiving channel, a frequency source and a power amplifier module; the digital module is connected to the radio frequency module and comprises a control module, a time service module, an AD module and a DA module and a record module; and the image processing module is connected tothe digital module and comprises a motion compensation module and an imaging processing module. The SAR system is built by adopting the FMCW system, main performance parameters of the system are designed based on the FMCW system, the advantages of simple system structure, small size, light weight and low cost are met, and the SAR system also has relatively high range resolution. Meanwhile, the actual application requirement is combined, and a processing method of the radar system is designed, so as to adapt to application requirements in many fields such as military reconnaissance, geologicalexploration, topographic mapping, ocean exploration as well as agriculture and forestry reconnaissance.