Abstract: Unequidistant bicubic B-spline function is employed in this paper to represent the displacement components of rotational shells under global coordinates. The periodicity condition demanded by the circumferential interpolating function is given. By using a penaltyelement method, the paper provides the compatible relations of composite shells under global coordinates. Compared with the conventional methods, the technique used in this paper is simple and clear, and easy to be understood. One example is presented.