Abstract: The interference characteristics of 3 different support struts commonly used in high speed wind tunnel tests for large aircraft are analyzed to provide some references in selecting support type, and the second-order interference characteristics caused by assistant support struts during sting interference test are also studied. Structural chimera grids are used to simulate Ty-154 standard model support by sting, belly blade and vane suspension, interference magnitudes are acquired respectively, and their interference mechanism is studied. Combination support type sting-blade and sting-vane are also simulated to investigate the second-order interference magnitude. The results show that numerical results coincide well with test data, proving the research results have a high fidelity. The sting support show much interference to the drag and pitching moment, while the vane support make little interference to them. The blade support make the drag increase much but shows little influence to the pitching moment. On the conditions of Ma>0.9, the interference magnitude increase rapidly and the blade support increase the most. In the experiment of sting interference correction, the second-order interference of blade and vane support is very small, and can be omitted in the engineer field.