Abstract: It is difficult to insure the quality of composites for the reason that there are complicated processes during curing process of composites. There is a We need to develop an advanced on-line monitoring system for the curing process of composites. It is feasible to develop fiber optic sensors to monitor the molding process of composite materials. As the development of fiber optic technologies, the physical parameters, chemical parameters and the mechanical parameters of composites during the molding process are mightily monitored. In this paper, the principle of sensing the molding process of composites by fiber optic is introduced. The feasibility of establishing the smart fiber optic-composites system is set forth. A sort of fiber optic sensor based on strength modulation is researched to monitor the process of composite during the curing process. The experiments were carried out in the laboratory and production field. It can monitor the curing process, including the lowest point of the resin matrix, the end point of curing process of composite material sensitively and precisely. The research results show that the technology can be applied to intelligently monitoring and controlling the molding process of composite materials. The successful application of the optic fiber monitoring system in the real production field shows that this technology has reached practicality ability.