In some areas, such as automatic control, electric measure, spaceflight projects and so on, data acquisition technology is used widely. USB has the characteristics of easy to use, high speed and supporting to cut in or pull out on-line, it becomes a trend in data acquisition technology. To introduce the hardware and firmware design, selecting floating point DSP for microprocessor and Philip Corporation's ISP1581 as USB receiver/transfer control chip. The hardware consists of signal conditioning circuit and USB interface circuit. Based on the analysis and understanding of USB protocol,the firmware is designed by modules and layers. Thus, it has sample structures and clear levels. Different modules and layers have different functions, and the programs convenience revise. At last, to introduce the problems during the debugging are analyzed and summarized, some measures about the system improvement are proposed. Thus, combining USB and DSP is an effective solution to data acquisition with high speed as well as processing and transmitting.