On-site　quantitative　detection　provides　the　opportunity　for　accurate　and　timely　health　care,　clinical　diagnosis,　environmental　monitoring,　and　food　analysis.　A　variety　of　portable　electrochemical　detection　instruments　have　been　developed　at　present　for　on-site　quantitative　detection　use,　including　commercially　available　portable　potentiostats,　but　the　reality　is　that　these　electrochemical　detection　devices　still　have　the　problem　of　narrow　output　voltage　range　and　detection　current　range,　and　their　performance　of　output　voltage　resolution　and　detection　current　resolution　is　still　unsatisfactory.　The　narrow　voltage　or　current　range　makes　it　difficult　for　some　chemical　reactions　with　peaks　outside　the　range　to　proceed,　and　the　insufficiency　of　voltage　resolution　and　detection　current　resolution　are　key　parameters　restricting　the　detection　accuracy　of　existing　devices.　In　this　regard,　it　is　urgent　to　carry　out　partial　transformation　of　the　existing　device　to　increase　the　use　range　and　detection　accuracy　of　the　device.　In　the　current　work,　a　smartphone-based　electrochemical　on-site　quantitative　detection　device　was　developed.　The　device　comprises　a　portable　small　potentiostat,　a　smartphone　equipped　with　a　specially　designed　Android　electrochemical　detection　application,　and　a　disposable　sensor　(NiONP　modified　screen-printed　electrode　[SPE]).　The　potentiostat　can　realize　electrochemical　detection　methods,　including　cyclic　voltammetry,　chronoamperometry,　and　differential　pulse　voltammetry.　In　addition,　the　potentiostat　can　output　a　potential　range　−2.047∼+2.047　V　with　a　current　detection　sensitivity　scale　1×10−8∼1×10−3　A,　and　the　current　detection　range　could　reach　±10　nA∼±10　mA.　Most　importantly,　the　current　detection　resolution　of　the　potentiostat　can　reach　0.003　%　(3.125　pA　on　±10　nA　range).　The　smartphone　was　used　for　communicating　with　the　potentiostat,　setting　detection　parameters,　and　mapping　voltammograms　in　real　time.　The　SPE　was　modified　with　nickel　oxide　nanoparticles　and　perfluorinated　resin　solution,　which　were　employed　as　sensors　to　convert　and　amplify　the　electrochemical　current　response　during　the　on-site　quantitative　detection.　Results　indicated　that　the　device　features　excellent　performance　for　the　lactate　detection.　The　device　covered　a　linear　range　0.1∼30　mM　on　lactate　detection　with　the　correlation　coefficient　(R2)　reaching　0.997.　©　2022　Wiley-VCH　GmbH.