Abstract: In order to solve the problem of rudder hinge moment flight measurement of a civil aircraft driven by reaction link actuator, the presently available hinge moment measurement method needs to simultaneously measure the axial/vertical load of actuator and the axial load of small connecting rod. However, due to the limitation of structural space, the strain bridge cannot be installed on the actuator, so the load measurement is difficult. In this paper, a novel model is proposed to calculate the hinge moment of the rudder indirectly by measuring the axial load of the small connecting rod which is not connected to the rudder surface. Firstly, the strain measuring position of the small connecting rod is determined by the finite element method. Secondly, the measurement model of hinge moment is established and verified by the off-line load calibration test and the hinge moment on-line verification test. Finally, the flight test results of rudder hinge moment model are obtained through the coordinated sideslip maneuver. The results show that the measured model are accurate and effective, meeting the flight test requirements, which can apply to the measurement of rudder hinge moment with the similar driving structure.