A Finite Impulse Response(FIR) digital filter based on Field Programmable Gate Array(FPGA) is designed and implemented for signal processing in strain signal acquisition system. Firstly, based on MATLAB, Blackman window function is used to design a 15 order digital filter with 16 length, and the signal is composed of white Gaussian noise and sine wave with frequency of 2 kHz and 8 kHz. Then the 12 bit coefficients are quantized, and the coefficient file is imported into QuartusⅡ 13.1 software. Combining with the IP core of digital filter in FPGA, FIR digital filter is designed from top to bottom. Finally, it is simulated in Simulink environment. The results show that the mean square error of the synthesized signal decreases by 28.5% before and after filtering, which can improve the quality of low frequency signal and enhanced the function and integration of the strain signal acquisition system.