Aiming at the problem that the echo of coherent laser wind lidar is very weak and the frequency domain amplitude of the echo cannot be obtained after direct fast Fourier transform(FFT), a digital intermediate frequency signal processing method embedded in field programmable gate array(FPGA) is proposed to effectively extract the frequency domain amplitude of the echo, The echo of laser wind lidar is the backscattered signal of coherent laser pulse through aerosol in the air, Due to the small aerosol concentration in the air and the limitation of laser emission power, the echo is extremely weak, Firstly, the analog signal of echo is amplified through the intermediate frequency(IF) amplifier, and then enters the analog-to-digital converter(ADC) for sampling, Then digital IF signal processing methods such as zero padding FFT and FFT spectrum accumulation are used to improve the signal-to-noise ratio of weak echo, so as to effectively identify the frequency domain amplitude of wind speed information in echo, Through the test, the stable wind speed within 2 km is obtained, and the accuracy is 0, 1 m/s,