Abstract: Abstract: In order to achieve high accuracy parameter estimation for LFM signal’s initial frequency and chirp rate, DAF algorithm based on discrete ambiguity function is investigated. This algorithm has advantage of low computational complexity, but parameter precision is limited by sample frequency and sample size. For solving this problem, a new method using DAF interpolation algorithm is addressed. LFM signal is transformed to sine signal by DAF, thus the pre-value of parameters are estimated by peak-searching after using FFT twice. Then according to spectrum subdivision technique, the pre-value is corrected by Rife interpolation through the max-spectrum and sub-spectrum firstly, and two discrete spectrums which are the neighboring 0.5 quantized frequencies secondly. The DAF interpolation algorithm breaks through the discrete interval resolution of DAF and gets high accuracy of parameter estimation with lesser computing complexity. The results of simulations verify the efficiency of this proposed algorithm.