Aerospace vehicle structure is affected by various factors and there are various flight safety problems in the long-term service process. With the help of fiber Bragg grating sensors， this paper proposes an optimization method for the calculation of curvature information aiming at the torsional and rotational bending conditions of the connecting rod structure. This method can reduce the data measurement error caused by the size of the grating grid area during the bending and torsion deformation of the rod， and thus improve the accuracy of deformation inversion. Moreover， ANSYS Workbench simulation results show that this method can reduce the average error of rod deformation monitoring and inversion under torsion / bending deformation by about 8%. The relative error before and after the optimization algorithm is reduced by 3.3%. Therefore. the research results show that the method is applicable to the monitoring of torsional deformation of member structures， and it can provide assistance for the service status perception and adaptive adjustment of future aircraft structures.