In　order　to　implement　the　tracking　control　design　towards　concentrations　of　dissolved　oxygen　and　nitrate　nitrogen　in　wastewater　treatment,　a　data-based　iterative　dual　heuristic　dynamic　programming　(DHP)　method　is　established　in　this　paper.　First,　the　optimal　tracking　control　problem　is　transformed　into　the　optimal　regulation　problem.　Then,　the　iterative　adaptive　dynamic　programming　strategy　is　introduced　to　solve　the　optimal　control　problem　of　the　new　system　with　the　discount　factor　in　the　cost　function,　and　the　convergence　analysis　of　the　iterative　algorithm　is　given.　Furthermore,　a　new　training　approach　is　used　to　adjust　the　weights　of　the　action　and　critic　networks.　Finally,　the　experimental　simulation　for　a　wastewater　treatment　plant　is　presented　to　verify　the　applicability　of　the　proposed　iterative　DHP　optimal　tracking　control　method.