Abstract: In order to meet the requirements of high space resolution, high spectral resolution, high time resolution, small volume and light weight for the remote sensing of pilotless planes, the off-axis three-mirror anastigmatic optical system is adopted. The asynchronous working mode is proposed for two cameras. The integration of data from the asynchronous cameras and the synchronous real-time output were realized by FPGA. The structure of the entire asynchronous image data acquisition system is introduced. The time sequence simulation was carried out with Modelsim 6.1 in the environment of Xilinx ISE7.1, and then the actual testing was performed. The experimental results show that the system is stable and reliable. Its focal length is f=70mm, relative aperture is D/f=1/6, angle of FOV is 2w=65and total weight is 6kg.