It is often necessary to perform a long one-dimensional sequence transformation or convolution. If the sequence is too long to process，the multidimensional techniques can be used. This article describes some methods of multidimensional processing to replace the method of one-dimensional processing，and gives out their distinct processing procedure. On the basis of this，this paper provides a compound algorithm WFTA-FNT，it takes good advantages of simplicity，speediness and accuracy of FNT，while the restriction on sequence length imposed by word length or the ambiguous representation of the output is avoided by WFTA.