This paper shows a new design for data acquisition system in automobile engine analysis instrument.Having been compared with some schemes, the system is characteristic of automatism, high-speed, vast-capacity, and real-time. Through adopting ping-pong memory access to DSP and FPGA/CPLD, and setting four modes, the system controls two slices of SRAM to write and read the data converted from A/D alternately. In this way, A/D acquires data uninterruptedly while DSP reads and processes the sample data. Furthermore the data pretreated by DSP communicate with upper ARM using the HPI that has function of DMA. Accordingly, the system realizes parallel communication of collecting data, pretreating and transmitring, while solves the problems including of depth of buffer, DSP control and FPGA/CPLD status. In this paper, the logic structure of FPGA/ CPLD was designed using VHDL and was simulated and analyzed. The design and debug of soft interface was completed by applying C language of DSP, which supply the driver for the software design on apply layer.