Abstract: The Y-eccentrically braced composite frame with double shear links (“DY-EBCF” for short) can ensure sufficient load capacity and lateral stiffness while minimizing the occupation of shear links on the lower building usage space. However, constrained experimental investigations incompletely validate the preeminence and universal suitability of the configuration, hindering the widely application in practical engineering. The theoretical model of DY-EBCF is established based on the load behaviour of each member, then the deformation mode and internal distribution are derived according to displacement method. The theoretical model indicates that, in comparison to the composite frame, the internal forces at both the end of the beam and the base of the column increase as the rotation at the beam end decreases. Besides, the added moment at the beam end and the installation position of shear links can be decreased by increasing the spacing between two shear links to minimize the damage of RC slab. The polylines-type theoretical skeleton curve of DY-EBCF is then proposed and the formulas for calculating the applied load and displacement of key points are both derived, the accuracy of this model is verified by comparing the theoretical result and test result. The influence of key design parameters of DY-EBCF in terms of beam-column stiffness ratio, shear stiffness of shear links, spacing between two shear links and stiffness of diagonal braces on the mechanical properties is discussed and the propositional value of these parameters are proposed.