In view of the problems existing in the current high-speed TV rendezvous measurement of rocket drift, such as the great influence of the external environment and the inability to obtain the measurement data in real time, an active measurement method of rocket takeoff real-time drift based on lidar is proposed. First, the lidar is installed on the two-dimensional precision turntable through the installation platform. In the process of rocket launch, the two-dimensional precision turntable drives the lidar to continuously track and scan the target point position of the rocket with high precision, and obtain the lidar point cloud data corresponding to the target point position. Then, the data processing system receives the lidar point cloud data, fits the elliptical curve and the elliptical curve center point of each frame data, takes the position of the elliptical center point when the rocket is stationary as the reference position, calculates the relative difference between the elliptical center point position of each frame data and the reference position, and determines the real-time drift of the rocket in the take-off stage. Finally, the measurement system and method are verified by the rocket launch test, and the test results show that under the condition of environmental interference, the measurement accuracy of real-time drift is 3.1 cm. It is the most accurate measurement method in the rocket drift measurement at present. At the same time, it can ensure the real-time performance of the data, provide real-time discrimination data for the rocket launch security console, and ensure the safety of the launch process.