Fiber Bragg grating (FBG) sensor is sensitive to strain and temperature during composite curing process. A new method is raised to monitor the temperature and strain with double FBG sensors during composite vacuum bag molding process. The gel point and pressured point are obtained and optimized. The experimental results show that the gel temperature and time obtained by FBG sensors and dynamic mechanical thermal analysis (DMTA) are very consistency, and the composite manufactured under optimum pressured point has excellent interface performance and no delamination in the middle layer from scanning electron microscopy (SEM). This method can realize monitoring and optimizing of composite vacuum bag molding process.