Abstract: In this paper, the error distribution of the frequency correcting value by the general phase difference correcting methods is studied. It is discovered that the frequency error is not even in the whole frequency interval and the frequency error near the 1/2 frequency interval is bigger than others. There is a peak on the frequency error curve near the 1/2 frequency interval. To solve this problem, then the weighting phase difference correcting methods on discrete spectrum is proposed and simulated. Since not only the main peak spectrum line but also the second peak spectrum line is considered in some radio. In this method, the frequency errors figured out by the main peak spectrum line and the second peak spectrum line are weighted average by the amplitude ratio of the two spectrum lines. Then the amplitude error and the phase error can be figured out by the frequency error and the windows function. The new methods can effectively stabilize the peak in the error distribution of the general phase difference correcting methods appeared far away the spectrum line. Thus the new methods further improved the accuracy of the correcting frequency and the noise immunity of the algorithm. In addition, the applicable region of the methods is discussed, which is the region near the 1/2 frequency interval. Through the correcting threshold the applicable region can be restricted, in order to improve correcting accuracy.