The　spatial–temporal　distribution　of　reactive　oxygen　species　(ROS)　in　human　tissue　is　critical　for　the　medical　applications　of　cold　plasma　jet　as　it　reflects　the　therapeutic　range　of　cold　plasma　jet,　but　the　mechanism　for　its　formation　is　still　unclear.　To　this　end,　KI-starch　reagent　was　used　to　visualize　the　surface　distributions　of　ROS　on　the　model　human　tissues　treated　by　a　He　+　O2　plasma　jet　in　this　paper.　It　was　found　that　the　surface　distribution　of　ROS　was　divided　into　two　parts　by　a　small　donut-shaped　of　un-colored　area.　This　un-colored　area　was　resulted　from　the　color　fading　of　the　model　tissue,　which　might　be　induced　by　the　AC　electric　field　of　the　plasma　jet　and　the　plasma-generated　reductive　species.　The　colored　area　and　the　un-colored　area　had　different　trends　with　the　working　gas　flow　rate　and　the　model　tissue　conductivity.　The　un-colored　area　increased　with　the　expansion　of　the　plasma　plume　and　shrank　with　the　increasing　model　tissue　conductivity.　Graphical　abstract:　[Figure　not　available:　see　fulltext.]　©　2022,　The　Author(s),　under　exclusive　licence　to　EDP　Sciences,　SIF　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.