In view of the facts that the random signals obtained in engineering usually have poor predictability and irregular wave shape, and based on studying the existing technique to extend end points,a practical method to restrain the end effect, i.e. extrema shift method, is proposed. According to the features of end points and the extrema near the end, four shifted extrema are added to each end of the signal respectively, with the purpose of restrain the end points from divergence. Decomposition results of simulation signal and measured response indicate that the proposed method possesses high calculation efficiency,and can relief the influence of end effect remarkably.