The high precision measurement of structure stress and strain has the vital significance for helicopter dynamic and static strength monitoring and assessment. Since the fiber Bragg grating (FBG) sensor has good flexibility， core diameter of fine， strong ability to resist electromagnetic interference， easy to realize distributed monitoring and other significant advantages， it is paid widespread attention in the field of aerospace plane structural strength monitoring. To improve strain monitoring accuracy and sensitivity of helicopter， FBG strain sensing principle and factors influencing the sensor precision are studied， and the plate-structural strain monitoring system based on FBG sensor is also constructed. The stripping coating layer of grating area， the prestress as well as the double-layer glue joint are presented， respectively. These pretreatment cementing methods are advantage to improve strain measurement accuracy of board structure based on FBG sensors.