Abstract: In this paper, a pulsar de-dispersion algorithm based on the Short Time Fourier Transform (STFT) is presented.First of all the reason of the pulsar dispersion and several popular de-dispersion algrithms are introduced.Secondly the Short Time Fourier Transform (STFT)algorithm is also introduced and a de-dispersion algorihm is proposed based on it.Thirdly, the process of this algorithm is described in detail, and a comparison of the de-dispersion results among different size of window functions is made.Finally, after the comparison among these algorithms, it is shown that this easy-to-implement de-dispersion algorithm needs less amount of computation, and can de-disperse pulsar signals effectively.