Abstract: As a new bridge structure component, the GQFGJX improved modular expansion device has been widely used in the Liupanshui-Weining section of Duyun highway to Shangri-La. Three full-scale test models were established for the middle beam and cross beam of this new expansion device, and static load test was carried out in order to study whether the strength and stiffness of the middle beam and cross beam selected by the new expansion device under vehicle load could meet the requirements of General specifications for Design of Highway Bridges and Culverts(JTG D60-2015). The results showed that the external bending stiffness of the middle beam was generally less than the internal bending stiffness. The ultimate failure mode of the expansion device under vehicle load was the instable failure of the middle beam caused by the out-of-plane buckling in mid-span. When the beam spacing was not more than 1.8 m, the stiffness and strength of the middle beam and the cross beam could meet the requirements of JTG D60-2015. Reducing the cross beam spacing could significantly improve the bearing capacity of the expansion device.