Most of the key components of aircrafts work in a complex loading environment that they are loaded by multi-axis force composed of tension or compression, bending moment and torque. The mechanical properties and fatigue life of key components have direct influence on the overall performance of the aeronautical system. Ensuring their safe and efficient service, it is necessary to test these properties under the load that close to the actual working conditions. In this paper, the elastomeric spheric thrust bearing (ESTB) is employed as the test object. Based on a 6–SPS parallel mechanism, a multi-axis loading device which is expected to simulate the ESTB’s actual working condition is developed. This device can load the ESTB with combined loading of pressure, bending moment and torque, and test the stiffness of the ESTB. The geometric parameters of the loading device were designed and its prototype was presented. Tests for compression, bending and torsional stiffness were conducted by the multi-axis loading device. Compared with the results obtained by traditional testing methods, the compression and torsional stiffness are in good agreement, but the bending stiffness is deviated because the traditional method didn’t eliminate the influence of axial force while applying bending moment. The tests prove multi-axis loading ability of the parallel mechanism. In addition, the stiffness characteristics of the ESTB under combined
pressure-torque is initially explored. Finally, the applications of the parallel mechanism in material tests and loading moving targets are discussed, and a multi-axis loading theory system for material, component and system could be formed.