The invention discloses a time domain clutter suppression method suitable for LTE external radiation source radar. According to the method, an original monitoring signal is subjected to sinc functioninterpolation to obtain a monitoring signal linearly combined by limited integer delay reference signals; the interpolated monitoring signal and the reference signal are segmented separately; the segmented monitoring signal, the reference signal and a filter weight are subjected to fast Fourier transform, so that the signal is transformed from the time domain to the frequency domain; clutter suppression is performed according to the minimum mean square algorithm in the frequency domain, and adaptive variable step weight updating is carried out; and finally, the output results of each segment are combined. Compared with the prior art, the method has the advantages that accurate estimation of the fractional delay time is not needed, the interpolated monitoring signal and the reference signalare subjected to batch minimum mean square adaptive filtering; and when the estimated value is close to the real value, the output result is the required target echo signal, the clutter suppression performance of the monitoring channel is improved, and the target detection of a radar system is facilitated.