In the laser inertial navigation system signal acquisition circuit is required to have high acquisition precision and small size.A simple method for designing data acquisition circuit with high precision and small size is presented here.FPGA is used in the method for acquiring laser gyro output signal and FIR filtering and I/F circuit is used to convert the quartz flexible accelerometer output current signal into frequency signal.The paper describes the design process of the circuit hardware and software of the signal acquisition circuit including I/F circuit design and FIR low-pass filter design.The correctness of the design is verified through a final experiment.