The　mixed　traffic　of　conventional　vehicles　(CVs)　and　connected　and　autonomous　vehicles　(CAVs)　will　dominate　a　long　period　in　the　popularization　of　CAVs　and　its　dynamics　are　still　not　clear,　especially　in　some　complicated　traffic　scenarios.　In　this　paper,　an　improved　cellular　automaton　model　was　applied　to　investigate　the　CVs-CAVs　mixed　traffic　dynamics　around　freeway　merging　area.　The　lane-changing　rules　were　improved　to　consider　the　difference　between　CAVs　and　CVs　and　also　the　variation　of　drivers＇　aggressive　driving　during　the　merging　process.　The　simulation　has　been　conducted　with　different　traffic　demands　and　percentages　of　CAVs　while　the　phase　diagram,　spatial-temporal　diagram,　characteristics　of　traffic　volume,　velocity　profiles,　stability　and　traffic　conflict　around　the　merging　area　were　obtained.　The　results　show　that　CAVs　contribute　to　improving　the　traffic　operation　of　freeway　merging　area　in　most　conditions.　However,　more　CAVs　in　the　merging　area　without　proper　management　will　have　a　negative　impact　on　traffic　if　the　traffic　demand　for　the　main　road　is　great.　For　example,　the　stability　can　decrease　and　particularly,　the　on-ramp　traffic　will　be　completely　blocked　when　the　percentage　of　CAVs　is　one.　The　findings　can　provide　a　basis　for　further　research　on　the　CVs-CAVs　mixed　traffic.