Abstract: A reinforcing brace structure for a furniture frame belongs to the technical field of furniture structures. The reinforcing brace structure includes a tube body, a lower slot, and an inverted L-shaped slot unit. The reinforcing brace structure enables the use of a tube body with a relatively large vertical dimension together with an inverted L-shaped slot unit having a relatively shallow vertical cut depth, thereby ensuring high structural strength of the reinforcing brace; The vertical cut depth of the inverted L-shaped slot unit is less than the vertical height of the side plate of the side longitudinal beam or intermediate longitudinal beam, leaving a residual vertical plate portion of the beam below the inverted L-shaped slot unit that engages with the lower slot. This engagement prevents the longitudinal beams from splaying apart and effectively inhibits the tube body from falling out.