This　study　developed　a　novel　strategy　for　enhancing　volatile　fatty　acids　production　from　waste　activated　sludge　by　cation-exchange　resin　assistant　anaerobic　fermentation.　The　process　condition　was　optimized　by　response　surface　methodology.　Considerable　sludge　disintegration　degree　(40.9%)　and　volatile　fatty　acids　yield　(4619.6　mg　COD/L)　were　achievable　at　the　proposed　process　conditions,　i.e.　cation-exchange　resin　dosage　=　2.05　and　1.78　g/g　SS,　fermentation　time　=　4.97　and　6.46　d,　and　stirring　strength　=　246.9　and　261.2　rpm,　respectively.　Grey　relational　analysis　revealed　that　cation-exchange　resin　dosage,　fermentation　time,　and　stirring　strength　presented　similarly　significant　effects　on　sludge　disintegration.　The　reusability　tests　showed　that　NaCl　solution　had　the　best　effect　on　cation-exchange　resin　regeneration,　and　the　performance　of　regenerated　resin　was　comparable　with　the　original　resin　on　volatile　fatty　acids　production.　Compared　with　conventional　pretreatment　methods,　the　proposed　cation-exchange　resin　assistant　strategy　revealed　obvious　advantages　of　saved　pretreatment　agents,　easy　operation,　none　chemical　residual　in　sludge　and　small　footprint.　Total　volatile　fatty　acids　recovery　can　reach　1.46　×　108　tons　chemical　oxygen　demand　annually　in　terms　of　China＇s　context,　which　could　offset　one　third　of　carbon　gap　in　China＇s　wastewater　treatment　plants.　The　proposed　cation-exchange　resin　assistant　strategy　indeed　sheds　lights　on　the　direction　for　WAS　treatment　in　a　close　alignment　with　process　viability　and　engineering　feasibility.　©　2020　Elsevier　Ltd