The invention discloses a method and a device for estimating sea surface wind speed based on line spectrum intensity in radar echoes. The method comprises the steps of establishing an experiential model in which intensities of a first-order peak and a secondary harmonic peak are changed along air speed, firstly estimating model parameters by fitting by taking air speed data measured in real time by virtue of a site buoy and air speed estimated on a radar close range unit by virtue of a conventional second-order spectrum method as standards, then estimating air speed by virtue of the intensities of the first-order peak and the secondary harmonic peak in an echo Doppler spectrum, weighting and combining the estimating model parameters with the air speed, so as to obtain a final air speed estimation value. According to the method and the device, the problem of high-frequency ground wave radar that an existing air speed estimation method based on an echo second-order spectrum is not accurate enough is solved; the intensities of a first-order Bragg peak and the secondary harmonic peak in the echo Doppler spectrum are related with the air speed value, so that the air speed can be directly extracted from line spectrums including the first-order peak, the secondary harmonic peak and the like, and the estimation precision of the sea surface wind speed by the high-frequency ground wave radar is substantially improved.