The posture of the laser head is requested strictly in the cutting along the intersecting line of laser processing robot, and the position model of intersecting line is complex. In order to meet these demands, a continuous trajectory planning method which is used to controlling the position and posture of laser head is proposed. For the normal direction of the surface keeping coaxial to the laser head, the posture of the laser head can be known by solving angle which is between the laser head and the cutting surface. A design on 3D visualization simulation for the laser processing robot under the VC++6.0 environment and the OpenGL is introduced. The simulation results show that the trajectory planning method can effectively control the position and posture of the laser head.