In order to extend the application range of ESPI to visualizing in real time airflow motion, a FFT followed by a digital phase only low pass filter and an inverse FFT were applied to ESPI carrier fringe patterns for removing speckle noise, and then the original ESPI carrier fringe patterns were replaced with the input images. The low pass filtered patterns were regarded as normal interference fringes that in high contrast and low noise, and airflow field information was contained in it. The change of spatial phase caused by the process of replacing image, and a correlative correction term in measurement of airflow field were obtained by a simulated test interferogram. A phase extraction method based on gray scanning was proposed for calculating phase difference in real time airflow motion,and phase extraction using Fourier transformation profilometry was carried out in spatial domain，also along the time axis. The temperature distribution were calculated using phase extraction.This method can be used in dynamic ESPI measurements of airflow field availably.
