To conduct long-term, stable, and real-time strain field monitoring of wind turbine blade structures, a fiber Bragg grating (FBG) sensor based on carbon fiber reinforced polymer (CFRP) packaging is designed, and a sensing system based on multiple FBGs is built. The FBG encapsulation is implemented using a CFRP-sealed aluminum foil structure. Simulation analyses are conducted to determine the stress field distribution across the blade at varying angles, providing a basis for FBG placement. In the static strain calibration experiment, the strain sensitivity at the 1 cm position of the FBG test site is 5.3 pm/kg, with the stress field exhibiting a radial distribution centered at the stress point. In real-time operational tests of the blade, FBG1 and FBG2 have the largest range of strain changes, with maximum and minimum strain values of 482 με, -472 με, and 462 με, -476 με, respectively. The effect of vertical strain on blades is much weaker than axial strain. The test data has a threshold range, which verifies that the system can evaluate blade operational status through threshold settings. This structural design, characterized by high sensitivity and superior tensile resistance, demonstrates promising application potential.