The invention discloses a pre-binding device of multi-size fabricated T-beam toothed block steel bars. The pre-binding device comprises a transverse steel bar separating frame and a longitudinal steelbar supporting frame. The transverse steel bar separating frame comprises two first bases arranged in parallel, wherein longitudinal vertical plates and longitudinal grooves are formed side by side in each of the first bases, the longitudinal vertical plates are provided with evenly spaced positioning holes, limiting plates with connecting holes at the bottoms are slidably arranged in the longitudinal grooves, and the limiting plates and the longitudinal vertical plates are connected by bolts arranged in the positioning holes and the connecting holes in a penetrating mode. The longitudinal steel supporting frame comprises bearing beams connected with a height adjusting mechanism, the bearing beams are perpendicular to the longitudinal grooves, and a plurality of limiting rings which are positioned by screws are arranged on the bearing beams in a penetrating mode. The pre-binding device can meet various design requirements and has wider applicability; and the pre-binding device is simple in structure, easy to use, convenient to assemble, split and transport, can be repeatedly used, and greatly improves economic and social benefits.