Abstract: The faraway lightning impinging on the receivers of High-Frequency(HF) radar has to be rejected since it raises the Doppler spectrum background noise level and so degrades the detection performance of HF radar.According to the singularity of lightning interference,an approach which can discriminate lightning and clutter in fractal dimension by computing the direction-fractal dimension of radar echo signal is first proposed in this paper.Then a smart threshold avoiding the impulsive burst lightning is obtained and employed to detect the lightning.Finally a segment or segments of corrupted data are interpolated via linear prediction technique.The measured data are processed and the excellent performance of presented approach is demonstrated.