LK optical flow is an accurate and efficient feature tracking method which can be used to improve the performance of the image registration algorithm. For the registration problem of image sequence by time, a real-time and robust registration algorithm combining LK optical flow and improved FAST corners was proposed. The improved FAST corners was tracked by using the LK optical flow based on image pyramid and the registration parameters were calculated by adopting a robust homography estimation algorithm. In the experimental part, a real image sequence by time was used to verify the performance of the proposed algorithm from two aspects: registration accuracy and registration speed. The average re-projection error was 0.16 with the processing speed of 30 Hz. The experimental results show that the proposed algorithm can extract stable FAST corners and match the features between images efficiently and accurately, which solve the real-time registration problem of image sequence by time.