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The mirror extending approach proposed by Zhao and Huang ９in EMD method is improved in this paper.Mirror extending manner of data is kept unchanged, but the approach for determining nvelopes is changed. When the end of data is obvio usly not extremum, the envelope is determined by the first inner extremum and the image value in the mirror, ignoring the value on the end. This improvement eliminates the frequency compression near the end and decreases the error.Meanwhile,tridiagonal equations are used and the calculation speed is much increase d.Thetemporal process curve is more important in reflecting the real physical process and comparablewithotherp henomena.Frequency mixing in IMFs makes it impossible.A highfrequencyreconstruction (HFR)approach is proposed to eli minate common frequency mixing and reconstruct an IMF with all high fr equency portions.By this approach, the IMFs without frequency mixing are obtain ed to express significative processes.The high frequency information restored in high frequency IMF can be extracted by general spectrum method. After obtainin g IMFs by EMD method, some of the theoretical and technological issues still exi st w hen using the IMFs.The consistency of IMFs with real physical process is discus sed in detail.By virtue of the approach proposed in this paper,the EMD method can be widely used in various fields.