In the process of high-speed flight, the aerodynamic load acts on the wing of the aircraft as the main bearing structure to produce strain. The monitoring of strain distribution in key regions of wing is an important basis for evaluating the health status of aircraft structures. Therefore, the research on strain monitoring and strain field reconstruction technology of wing structures has important theoretical and practical significance. In this paper, a strain field monitoring and reconstruction method for large aspect ratio wing scaling model based on distributed optical fiber sensor and mode superposition principle is proposed. With the help of ANSYS finite element analysis software, the strain distribution and strain mode shapes of the wing model with large aspect ratio under different loads are simulated numerically. On this basis, by deploying fiber Bragg grating sensors in the direction of large aspect ratio aluminum alloy wing scaling model, strain distribution and variation information are collected in real time. Combining with the strain mode shapes of the wing model obtained by numerical simulation, the strain field distribution of the wing scaling model is reconstructed. The average error of strain inversion is about 7%. The results show that the proposed method has the advantages of non-visual measurement, good real-time performance and high inversion accuracy. It can provide technical support for acquiring timely and accurate strain field distribution information of aircraft wing surface, and then realizing aerodynamic load calculation and fatigue life prediction of aircraft wing.