This paper expatiates on the bus structure and develop the bus mode Multi-Channel Analyzer (MCA). The nucleus of this MCA is the PC/104 embedded computer, and it introduces the bus communication to realize system and data communication. It may realize data collecting and showing in the field, because the bus mode is rapid. At first, on the hardware we introduce CMOS components, this reduces power, volume and weight. These make it adapts to use in the field; besides, on the software we adopt C and assembly language to program in order to improve conversion speed. At the same time, single-task DOS operating system is infroduced, which makes the software run more steadily, operate more simply. By means of testing on the spot it can normally work, so it suitable to work in the field.