Abstract: The main pipe rotating welding scheme for intersecting pipes can reduce technology complexity and improve welding quality by achieving whole process of horizontal vertical position welding. In order to realize the automatic welding for intersecting pipes, the automatic welding model of intersecting curve with main pipe rotating welding scheme is established. On the basis of the geometrical model of the intersecting pipes, the welding seam feature and the welding torch pose are analyzed with homogeneous transformation matrix. After that, the main pipe rotation angle and the welding torch's position and posture relative to the world frame are formulated. The geometrical model of the intersecting pipes and the kinematic model of the welding process are simulated by MATLAB and OpenGL respectively. The simulation results show that the automatic welding model is feasible and can be used for the real-time interpolation and the off-line programming of automatic intersecting curve welding.