To meet the demand for monitoring the morphing wing aerodynamic shape of morphing aircraft, a flexible composite skin embedded optical fiber shape sensing method for variant aircraft was proposed. The fiber Bragg grating sensor was embedded into the thin layer of silicone rubber, then combining the silicone rubber layer with polyvinyl chloride sheet to form composite skin. The flexible skin shape sensing system was established, and the optical fiber sensing demodulation system was used to test the reflection spectrum characteristics of the fiber Bragg grating in the flexible skin under different airfoil. The morphing curvature of the flexible skin was calculated and the three-dimensional shape of the flexible skin was reconstructed. The contrast test was completed by the digital photogrammetry system. The results show that the measurement error of flexible composite skin deformation optical fiber sensing compared with digital photography is less than 4.62%, and the sensitivity of optical fiber sensing reaches 245.5 pm/m-1. The effectiveness of the embedded fiber sensing method is verified, which provides a reference for monitoring the morphing wing aerodynamic shape of the morphing aircraft.