The invention provides an FMCW SAR 
phase synchronization method based on distributed satellites. The method comprises the following steps: at any time t, emission 
satellite output signals are emitted after being respectively subjected to K frequency multiplication and N frequency multiplication; and then 
frequency mixing with carrier frequency signals is carried out after M frequency multiplication, and emission-end carrier wave phase differences are obtained through 
frequency spectrum peak extraction. One path of receiving 
satellite output signals are subjected to 
frequency mixing with echo signals after K frequency multiplication, and thus dual-
station echo signals are obtained; one path of the receiving 
satellite output signals are emitted after M frequency multiplication; and one path of the receiving satellite output signals are subjected to 
frequency mixing with the received emission signals after N frequency multiplication, and receiving-end carrier wave phase differences are obtained through 
frequency spectrum peak extraction. According to the invention, the emission-end carrier wave phase differences and the receiving-end carrier wave phase differences at any time t can be obtained by use of such a process, and compensation phases of the dual-
station echo signals are obtained after difference 
processing is performed on the emission-end carrier wave phase differences and the receiving-end carrier wave phase differences. According to the invention, the 
measurement frequency of the carrier wave phase differences can be improved, and the 
phase synchronization precision is improved.