The fabricated H-shaped steel web opening energy dissipation support is a new type of energy-consuming support composed of web opening H-shaped steel and force transmission channel steel connected by bolts, which can effectively avoid the instability of supporting members. In order to study the energy dissipation capacity and failure mechanism of this support, low-cycle reciprocating loading tests and finite element simulation analysis were performed on the specimens. The results show that the fabricated H-shaped steel web opening energy dissipation support has a full hysteresis curve, strong energy dissipation capacity and good deformability. Under the action of axial load, the test piece mainly relies on the short columns between the holes of the open web to enter the plastic energy dissipation. The ends of the short columns between the holes are the weak parts,which first enters the plastic during the loading process, and the fracture occurs first. With the deepening of loading, the plastic area in the middle part of the short column between holes becomes large and large. During the loading process, the bolts and channel steel are always in an elastic state. The specimen is eventually damaged due to the fracture of the short column between the holes. When the length of H-shaped steel energy dissipating web is the same, the wider the web width, the greater the height-width ratio of the short column between the holes, the smaller the bearing capacity and stiffness of the energy dissipation support, the better the deformation ability, and the short column height-width ratio between the holes in the range of 5-8 is more reasonable. It is recommended that the shortest distance from the arc at the end of the oblong hole to the center of the bolt hole be controlled between 1.2d₀ and 1.5d₀. Changing the arc radius of the oblong hole has little effect on the mechanical properties of the support. When the width of the H-beam web is the same, the greater the web length, the greater the bearing capacity and stiffness. The design method and ultimate bearing capacity formula of fabricated H-shaped steel web opening energy dissipation support are give.