In　municipal　wastewater　treatment　processes　(MWWTPs),　the　object　of　optimal　operation　is　to　guarantee　water　quality　standard　and　reduce　operation　cost.　To　achieve　these　goals,　it　is　necessary　to　update　the　optimal　set-point　values　of　operation　variables　in　MWWTPs　in　real　time.　However,　the　MWWTP　is　a　complex　system,　which　has　multi-variables,　multi-conflicts,　multi-objectives,　multi-constraints,　dynamics　and　time-varying　delays.　Therefore,　to　realize　the　optimal　operation　of　MWWTPs,　two　important　problems　are　how　to　design　the　accurate　operation　indices　models　of　MWWTPs　and　how　to　optimize　the　set-point　values　of　operation　variables.　In　this　paper,　some　existing　optimal　setting　methods　of　MWWTPs　are　reviewed.　Firstly,　the　characteristics　of　MWWTPs　and　the　optimal　setting　problem　are　introduced.　Secondly,　the　mechanism-based　and　data-driven　operation　indices　modeling　methods　of　MWWTPs　are　described,　respectively.　Then,　the　optimization　algorithms　for　single　operation　variables　and　multiple　operation　variables　are　given,　respectively.　Finally,　some　future　work　about　the　optimal　setting　methods　of　MWWTPs　are　discussed.　Copyright　©2019　Acta　Automatica　Sinica.　All　rights　reserved.