Abstract: During fabricating curved composite laminate, frictional slipping processes in prepreg stack and between prepreg and mold occur. The slipping degree has significant effect on the manufacturing quality of composite. In this paper, a testing device was established to evaluate the frictional slipping behavior of prepreg systems. By means of this equipment, the frictional resistances of carbon fiber/epoxy prepreg and prepreg and prepreg and tool materials, including steel, aluminum and rubber, under different processing parameters were analyzed. The experimeantal results indicate that the change of temperature can alter the frictional mechanism in prepreg stack, while the variation of exteral pressure does not change the frictional mechanism in prepreg stack. High temperature and low external pressure decrease the frictional resistance in prepreg stack, and further the slipping behavior. In addition, the surface roughness of tool material has great effect on the frictional slipping property between prepreg and tool, and the frictional resistance is influenced by the temperature rather than the external pressure.