Abstract: It is compared and analyzed that the failure mechanism,bearing capacity,deformation and rupture forms of edge joints through loading test with and without reinforced concrete flat beams,whose width height ratio is 3.It is also made a breakthrough at the requirements for section width limit of flat beams in Code for Seismic Design of Buildings(GB50011-2001),which provides a reference provided for design methods and engineering application of edge joints for reinforced concrete flat beams.