Abstract: To make the connection stronger than the components being connected in the aseismic design of braced frame, and to ensure the low-cycle fatigue life of a gusset plate being longer than that of bracing member, key parameters used in design are studied using an ANSYS program. The influences on the low-cycle fatigue life of a brace system (bracing member and gusset plate) are obtained by changing the angle between the brace and the column, the distance between the brace end and the assumed line of the restraint for the gusset plate, the thickness of gusset plate, the slenderness ratio of bracing member, and the ratio of free outstands of I-section brace flange to its thickness (b/t). The aseismic design suggestions of the gusset plate are given according to the brace slenderness ratios and b/t ratios of an I-section brace flange.