According to the weak characteristic of the output signal of accelerometer, we design a high precision data acquisition system based on TMS320F28335, CPLD and AD7760. The output signal of accelerometer after signal conditioning circuit go into 24 bit precision AD7760 to complete analog to digital conversion, DSP TMS320F28335 as the main controller control CPLD to read and write AD7760, DSP also send the collected data to the PC via the serial port. This paper introduces the design of system hardware in detail, including the signal conditioning circuit and the interface circuit between ADC、CPLD and DSP. This paper also introduces the software design of the system. The results of experiment show that, the data acquisition system designed can compete the task of acquiring weak signal.