Considering　the　current　maturity　level　of　autonomous　technology　and　the　general　public’s　acceptance　of　this　technology,　the　connected　mixed　platoon　mode　may　be　a　practical　transitional　strategy　prior　to　the　widespread　deployment　of　fully　autonomous　platoons.　To　study　the　influence　of　connected　condition　and　platoon　mode　on　the　operational　characteristics　and　eco-safe　influence　of　connected　mixed　platoon,　this　paper　constructed　a　connected　mixed　platoon　mode　consisting　of　five　vehicles:　a　human-driven　leader　vehicle　equipped　with　an　L2　connected　driving　assistance　system,　followed　by　connected　autonomous　vehicles.　Thirty-six　participants　were　invited　to　participate　in　driving　simulation　experiments　using　the　developed　test　platform.　Given　that　time-domain　analysis　focuses　on　the　variation　of　indicators　in　the　time　dimension,　while　frequency-domain　analysis　can　explore　the　frequency　distribution　characteristics　of　indicators,　this　paper　analyzed　vehicle　operation　characteristics　from　the　time　and　frequency　domain　dimensions　with　indicators　of　speed,　acceleration,　fuel　consumption　and　speed　safety　entropy.　The　results　show　that　both　the　connected　condition　and　the　platoon　mode　contribute　to　stable　vehicle　operation　and　significantly　enhance　their　eco-safety.　Compared　with　the　traditional　single-vehicle　mode,　the　connected　mixed　platoon　has　the　best　comprehensive　efficiency　and　can　reduce　the　fuel　consumption　by　10.　67%　and　the　speed　safety　entropy　by　73.　25%.　The　research　results　can　provide　scheme　reference　and　platform　support　for　autonomous　driving　enterprises　and　industries　in　executing　connected　HMI　design,　navigate　on　autopilot　(NOA)　development,　and　the　feasibility　and　effectiveness　test　of　connected　mixed　platoon.　©　2024　South　China　University　of　Technology.　All　rights　reserved.