Abstract: Poststack seismic signals is continuous in lateral direction,in terms of this property,we can construct suitable polynomial to fit seismic signals for improving S/N.however,3D seismic data fitting by traditional 2D polynomial often causes energy jumping.3D orthogonal polynomial fitting can effectively avoid energy jumping phenomena,but the method leads to abundant of human-computer interaction and huge computation.Therefore,we proposed a new implicit orthogonal polynomial fitting method,which not needs computing orthogonal polynomial any more.In addition,the new fast scanning technique can quickly and automatically process huge 3D seismic data without human intervention.The processing on real data shows that this method has great denoising effect on 3D poststack seismic data.