This paper

based on Fourier-transform-based Harmonic Analysis Algorithm

proposes an improved algorithm to overcome the drawback of artificially setting key parameters and to reconstruct high-quality time-series data.Firstly

outlier detection algorithm

instead of threshold setting method

is used to find unreasonable data points before curve fitting.Then

regarding the inherent phenological regulation for each land cover

Numbers of Frequency（NOF） is calculated pixel by pixel by polynomial fitting

which is more reasonable than setting a unique global NOF for the whole scene which contains complex land cover types.Fitting-effect Index

instead of manually setting one fitting tolerance

is employed to decide automatically when to terminate the iteration.The improved method is validated by the MODIS

E

VI time series of Huabei plain of 2003.The widely used Harmonic Analysis of Time Series（HANTS） is chosen as a comparison.The result shows that both of the two methods can reflect the phenological regulations of land covers

the reconstructed EVI temporal profile of single-season cropland（e.g.cotton） takes on one peak pattern

and those of double-season cropland and inland water take on double peak pattern and low-steady curve.But the improved method performs better in tracking the change tendency of the original curve.Moreover

the peak time and peak value of croplands are mostly consistent with the original curve

which will be useful for VI-based crop yield prediction.