Abstract: A multi-mode image acquisition and processing method based on FPGA is proposed. The proposed method can meet the different requirements for image update rate and pre-processing approaches, when the visible light sensor operates in attitude measurement mode or target tracking mode. This method realizes the pipeline operation of image sensor exposure, image acquisition and pre-processing. The FPGA controls the exposure, then captures window images of different sizes and selects the corresponding image pre-processing method, according to the functional mode set by the processor. During the image acquisition procedure, the FPGA can automatically adjust the image update rate according to the window size when receiving the image data from the image sensor. By conducting star observation and target tracking experiments, it is proved that the proposed multi-mode image acquisition and processing method can satisfy the operating demands of these two functional modes for the visible light sensor.