Abstract: To address slippage issues at the end of a multi-function laying head, a prepreg tape laying trajectory planning method for robot placing carbon fiber composite material is proposed. First, laying angles and center angles are obtained based on a prepreg tape laying path model. A differential geometric solution is applied to transition from dynamic to static coordinates based on the center angle, enabling calculation of the paving pose. Second, the convergence speed and calculation accuracy are enhanced by refining the original Snake Optimization Algorithm and incorporating it into the inverse kinematics of the laying robot. Inverse kinematics is employed to obtain the joint angles of the front seven axes of the laying robot from the laying pose. Matching the joint angles to the center angles effectively suppresses slippage at the end of the placement head. Finally, simulations and experiments are conducted on in-situ molding of ellipsoid shell tow laying. The results demonstrate no occurrences of slippage or wrinkles during the in-situ molding experiment involving the laying out of tows for unequal pole hole shells. The laying pose accuracy reaches 10⁻¹⁶, meeting the precision requirements for in-situ molding pose of tow laying, thus making it suitable for practical applications in tow laying in-situ molding work.