Because of the disadvantages of traditional video acquisition devices, such as large volume, simple processing capability and low flexibility, an image acquisition and processing system based on DM642 and CPLD chips is proposed. In the system, the DM642 chip is used to configure a TVP5150 video decoding chip for reading out video image data and processing them. A SAA7121H video coding chip is used to process the data and output them. The CPLD chip is used as the logic controller of the system. The experimental result shows that this system has achieved its desired effectiveness. In the future, the system will be used in the infrared thermal imaging for large space fire detection.