Abstract: A method based on image processing is proposed to measure the zero time of launching, after the analysis on the disadvantages of the current methods. The method is a non-contact measurement based on high frame rate camera and image processing technique. It considers the change in horizontal projection of the feature area to be the horizontal displacement of the target. When the displacement is larger than the threshold, the zero time is triggered. An experimental simulation considering different factors has been carried out according to actual situations. The results reveal that, the algorithm can provide real-time and reliable zero time signals by detecting 1 cm movement at a distance of 300 m in 10 ms.