Aiming at the failure problem of an array detection point of a fibre Bragg grating (FBG) curve shape sensor, this paper constructs a model based on double-array FBGs to solve the curvature and bending direction of the curve shape sensor. Firstly, the function relationship between the centre wavelength drift and curvature is derived, then the mapping relationship between curvature and bending direction is constructed, and finally the Frenet-Serret equation is used to achieve the curve shape reconstruction. On the basis of Ansys modelling and simulation analysis, this paper fabricates the FBG curve shape sensor and analyses the experimental data. The simulation and experimental results verify the feasibility of the dual-array FBG curve shape reconstruction proposed in this paper. Compared with the typical three-array FBG curve reconstruction method, the distal position errors of the simulated arc and s-shape increase only by 0.9% and 0.13%, respectively; and the average distal position error of the experimental data increases only by 0.34%.