A　new　scheme　is　proposed　for　realizing　entanglement　swapping　in　cavity　QED.　The　scheme　is　based　on　the　resonant　interaction　of　two-mode　cavity　with　A-type　three-level　atom,　and　it　involves　only　a　single　measurement.　In　the　scheme,　the　output　state　after　swapping　is　exactly　the　maximally　entangled　state　in　principle,　thus　it　is　prior　to　the　previous　one,　in　which　the　output　state　is　just　approximate.　Calculations　indicate　that　our　scheme　is　less　influenced　by　an　error.