Abstract: ISAR imaging of airplane has been researched thoroughly in China. But research on ISAR imaging for ship, which is also very important in national defense, is very little. Although the difference is little in principle between airplane imaging and ship imaging, the pose variation of ship is more complicate for the fluctuation of sea, so it need to be studied specially. This paper employs Range-Instantaneous Doppler Algorithm (RIDA) based on multicompo-nent Amplitude Modulation and Linear Frequency Modulation (AM-LFM) signal parameter estimation method to obtain good ship ISAR images from real data.