Abstract: During the laying of long-distance pipelines, pipe butt is always one of the construction difficulties faced by the field technicians, and accurately drawing the cutting trajectory is the key to improve the quality and efficiency of pipe butt.Therefore, a pipe butt model was established based on 9 basic variables according to the field condition of pipe connection.Then, the equations for the cutting trajectories of two pipes in a local spatial coordinate system were obtained through the calculation with the spatial analytic geometry method, and the coordinate transformation matrix between the two coordinate systems was also provided. Thereby, the cutting quantity of the pipe to be connected was calculated automatically by programming according to the calculation process, and measurement tests were performed for the relative position and cutting quantity of the pipe. The results show that no gap or overlay appears at the connection between the upstream and transition pipes in the butt model, and the starting and ending points of cutting trajectory drawn are coincided perfectly, which further verify the feasibility of the calculation method for cutting quantity of the butt pipe and could provide technical support for the onsite pipe butt and cutting.