The high spatial resolution, high accuracy, as well as real-time capability of distributed fiber-optic sensors are important for real-time structural health monitoring. As one of the promising technologies, the optical frequency domain reflectometry (OFDR) based sensors, have attracted lots of attention. Currently, for the demodulation, the conventional method based on short time Fourier transform requires long computational time, while a recent method based on group delay can remarkably improve the calculation speed but has low noise tolerance. In this study, we propose a fast demodulation method which employs the cross correlation, weighted sliding windowed Fourier transform and logistic activation function based thresholding process. This approach keeps good balance among the high spatial resolution, high accuracy, and the real-time capability that is expected to further improve the applicability of OFDR based sensors.