In the actual sewing process, the clothing styles are diverse, and the sewing parts are complex. There are different seam type requirements for different parts. Sewing components such as pockets, chest linings, front and rear sheets are made up of straight lines and curved edges of different shapes. The operation trajectory of the robot is difficult to plan, especially for the sewing of curved edge cutting pieces. Aiming at the problem that it is difficult to carry out complex performance measurement and mechanical modeling for fabric, this paper proposes a robot sewing method based on process modeling. The robot complex sewing task is divided into two parts : straight line and curve. Based on the ductility, the sewing tension is predicted, and the robot linear sewing based on the expected tension is realized. At the same time, the trajectory planning is carried out on the basis of the line identification of the curved edge to realize the curve sewing. Finally, the robot complex stitch sewing under different curvatures is realized on the built physical experiment platform. It is verified that the effectiveness of the robot sewing method based on process modeling.