High-frequency(HF) skywave over-the-horizon radar(OTHR) looks down its targets from the ionosphere,it has a large operating range and a large cover areas,but it also receives strong backscatterer echoes from the terrain and sea,and interference,such as radio frequency interference,industrial interference,impulsive noise,lightning impulsive,meteor trail echoes and so on.Interference can be divided into long time interference and transient interference.Transient interference lasts a short time,but its intensity is great.This paper first discusses the character of transient interference,then discusses its excision method,finally the method has been successfully applied to the real data from China experimental OTHR.The transient interference excision method is:first eigen-decomposition is used to separate the sea clutter subspace and filter it or ground clutter is filtered in frequency domain directly,then the transient interference can be detected,after that the original echoes with existing transient interference are excised,finally the excised clutter and target echoes are predicted by Burg linear prediction algorithm.