Abstract: A new improved permutation algorithm for radix 2 fast Fourier transforms (FFTs) is discribed. The algorithm provides an improved way for obtaining the bit reversal index table and affords an alternative data permutation methods. First, The algorithm divides an index with two parts, one is called group-index, which represents the index belonging to some group, and the other is called group-member which represents the order in the group. And then two arrays are used to store the values of the group-index and group-member power. According to the relationship between the bit reversal values of group-index and group-member, any bit reversal table can be obtained with the known one, which is (0,2,1,3). Second, when the data are needed to permute, the improved algorithm avoids the comparison operations between the index and its corresponding bit reversal value, which are required in the general permutation algorithm. In order to test its performance in the windows operation systems, several algorithms are programmed with C++ language, and their operation times are compared. The experiments show that the performance of the improved algorithm introduced in this paper is superior to that of the relative algorithms.