Abstract: To explore the mechanical behaviors and failure modes of a spliced plate-girder with cantilevered segments in a boiler steel structure, and to verify the design reliability of this type of girder in practical engineering, the static test for a reduced scale model and nonlinear finite element analysis by Abaqus Program are carried out. The loading capacity, local stress, flexural deformation, local buckling and other key performances at every loading stage, for both the simply supported segment and cantilevered segment, are analyzed with a reasonable explanation. The behaviors under bending moment and shear force are also studied for the bolted end plate splice, connecting the simply supported segment and cantilevered segment. Test and simulation results can both prove that the plate-girder is in a linear elastic stage under design loads, and has enough safety redundancy in subsequent loadings. The loading capacity of the spliced plate-girder depends on two major types of failure modes, i.e. the local buckling on webs near supports and fracture of splice bolts on the support plate. According to the internal force distribution in the splice, it can be assumed that the bending moment and shear force in the cantilevered segment are transferred separately to the bolts near the upper flange and the two webs. The accuracy and practicability of the simulation method are also verified by its well agreement with test results.