Composite structures are very susceptible to almost invisible impact damage induced by low velocity impact during the service of the aircraft, which can be fatal if not detected in time. Thus realization of real-time impact monitoring of composite structures is of great significance for the structural health of aircrafts. In this paper, a low velocity impact localization system and localization algorithm for composite reinforced plates using fiber Bragg grating sensors (FBG) were investigated. A high speed FBG interrogator is used to sample the impact strain time domain signals at 19200 Hz and impact localization algorithm based on objective function is used to estimate the impact location. The time difference between of arrival of the different sensors is determined by the cross-correlation function, and an objective function is constructed to estimate the impact position based on the time difference of arrival and the sensor position information. After that, the algorithm is verified on the composite reinforced plate. The experimental results show that the average positioning error of the algorithm in a monitoring area of 360 × 360 mm is15.94 mm. As it does not require a reference database, it is convenient for the development of impact monitoring airborne systems in the future and has broad application prospects.