A　quasi-static　experimental　research　program　is　presented　in　this　paper.　Six　full-size　concrete-filled　square　steel　tube　column　to　steel　beam　connection　specimens　were　tested　under　low-cycle　reversed　loading　at　the　ends　of　beams,　including　three　types　of　connections,　namely　side-plate　welding　(SPW)　connection,　stiffened　end　plate　(SEP)　connection,　and　the　normal　bolt-welding　(NBW)　connection.　The　hysteretic　behavior,　degradations　of　strength　and　stiffness,　ductility　and　energy　dissipations,　the　modes　of　failure　of　the　SPW　and　SEP　connections　were　compared　with　those　of　the　NBW　connection　under　different　axial　compression　ratios.　Based　on　test　results,　possible　failure　modes　of　these　connections　were　identified　as　joint　failure　or　steel　beam　cracking　or　buckling.　It　can　be　concluded　that　the　seismic　behavior　of　the　SPW　connection　and　the　SEP　connection　are　better　than　that　of　the　NBW　connection.