Dynamic envelope curve is one of the key factors to be considered when defining the dynamic gauge. To accurately obtain the dynamic envelope curve is one big step in design vehicle and also an insurance against dangers in driving. Since the major way to obtain dynamic envelope curve now is by enormous calculation, a measurement system is designed for measuring dynamic envelope curve of high-speed train. Based on binocular vision, the system produces the feature using high power pulse laser, and obtains the dynamic envelope curve of the high-speed train by high-speed acquisition, process and calculation of information that reflects the excursion of train. One field calibration method is proposed to build quickly and efficiently both the position relationship between the two cameras and the transformation between center coordinate system of railway and coordinate system of measurement system. It is proved by experimental results that the measurement precision of the system can reach up to ±0.5 mm, and that the measurement of the dynamic envelope curve of high-speed train is accomplished with high reliability, which can provide useful statistics for the definition of dynamic gauge of high-speed train.