The　performance　of　one-way　and　two-way　continuous　variable　quantum　key　distribution　(CVQKD)　protocols　can　be　increased　by　adding　some　noise　on　the　reconciliation　side.　In　this　paper,　we　propose　to　add　noise　at　the　reconciliation　end　to　improve　the　performance　of　CVQKD　with　untrusted　source.　We　derive　the　key　rate　of　this　case　and　analyze　the　impact　of　the　additive　noise.　The　simulation　results　show　that　the　optimal　additive　noise　can　improve　the　performance　of　the　system　in　terms　of　maximum　transmission　distance　and　tolerable　excess　noise.