To study the bearing capacity, lateral stiffness, ductility, and failure mode of high-strength steel composite Y-shaped eccentrically braced steel frames under horizontal loads, pushover tests were conducted on a half-scale three-story specimen. The test adopted three-mass inverted triangle proportional loading, and used OpenSees software to establish a corresponding numerical model for simulation. The results show that under the action of horizontal load, the link begins to yield, and the stiffness of the structure gradually decreases as the load gradually increases. During the test, the plasticity of the link on the second floor of the structure is the most obvious, the inter-story drift is the largest, and the inter-story drift ratio reaches 0.0433 rad. When the structure is finally damaged, it is manifested as the failure of the joints between frame beam and link, and the frame beams and columns are still in an elastic state.When modeling in OpenSees, the connection between the link and the frame beam is adopted using the method of rigid link and rigid section. The pushover curve simulation results obtained by this modeling method are in good agreement with the test results, indicating that the numerical model can be used for the simulation analysis of the seismic performance of the global structure. The parametric analysis results show that the lateral stiffness and bearing capacity of the shear link are better than those of the shear-flexural link.