In order to get a wide range of angles of attack, pre-bending support joints were used in rotary balance test. The pre-bending support joint was located in the model wake region at low angle of attack. The pre-bending support joint can cause interference with aerodynamic force and aerodynamic moment of model. The test was carried out by installing the pre-bending support joint at a symmetrical negative angle and rotating the model by 180 degrees. The test results show: the aerodynamic characteristic of the SDM model were interfered by the pre-bending support joint, when the pre-bending support joint was located in the model wake region at low angle of attack. But the interference of pre-bending support joint mainly caused the translation of the aerodynamic characteristic curve, and the interference of pre-bending support joint had little effect on the rotation derivative. The interference correction method proposed in this paper is very simple, which can provide a convenient and fast test method for the research of interference correction of the pre-bending support joint in rotary balance test.