Structural health monitoring technology can provide methods for flight test load assessment of aircraft active surface to verify the effectiveness of load design method and analysis data, and to provide the most direct data reference for safety verification and optimization of the active surface structure. The instability of traditional strain gauges in low-temperature environments may cause abnormal data collection. It makes the real-time monitoring and assurance of accuracy of flight load a difficult problem. This paper proposes a method using fiber Bragg grating (FBG) sensors based on stable low-temperature performance, for flight load evaluation of the connecting panels by establishing the strain-load relationship model under the tensile and compression load conditions of the structure via theoretical analysis, finite element simulation and tests, and provides a FBG sensor optimized layout method for strain and load assessment requirements of typical connecting panels of aircraft. The results show that the strain-load inversion method based on FBG sensors is effective and can meet the strain and load monitoring requirements of typical actuator connecting panels.