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 energy dissipation support of fabricated H-section steel webs 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. The plastic first enters the plastic during the loading process, and the fracture occurs first, and the holes are short. The area of the middle part of the column that enters the plasticity as the load goes deeper and larger. During the loading process, the bolts and channel steel are always in an elastic state. The specimen was 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-dissipating support, the better the deformation ability, and the range of the short column height-width ratio between the holes is 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 the energy dissipating brace with holes in the fabricated H-section steel web are given, which can provide references for engineering applications.