The invention relates to a method for compensating the tail end pose error of a non-decoupled six-degree-of-freedom mechanism caused by aerodynamic load. The comprises the steps of: obtaining the pose of the tail end of an aircraft model, establishing an elastic deformation error database of the tail end of the aircraft model under the influence of the aerodynamic load, obtaining the tail end pose error by using the elastic deformation error database, and obtaining a rotation angle compensation amount of a servo motor by using mechanism kinetic inverse solution or retrieval of the tail end pose compensation table. In a subsequent wind tunnel test, according to the pose and the aerodynamic load of the tail end of the aircraft model, a compensation value is quickly searched out in the elastic deformation error compensation database to compensate for the tail end pose error of the aircraft model. Such steps can reduce a complex measurement computational process and shorten corresponding test time. More importantly, the error compensation method can improve the overall wind tunnel test efficiency in order to ensure the smooth operation and the reliability of the wind tunnel test.