Knock　is　one　of　the　crucial　challenges　facing　direct　injection　(DI)　hydrogen　engines.　In　this　study,　the　rational　optimization　of　operating　parameters　and　the　proposal　of　two　progressive　knock　suppression　strategies　enable　the　DI　hydrogen　engine　to　achieve　knock-free　operation　at　wide-open　throttle　(WOT)　and　stoichiometric　conditions,　which　may　better　control　the　test　system＇s　complexity.　The　present　work　uses　0.5　bar　knock　intensity　(KI)　as　the　threshold　for　occurring　knock.　The　test　consists　of　three　parts.　In　Part　1,　KI　exceeds　0.5　bar　at　1.7　λ.　Then,　considering　the　suppression　effect　of　the　stratified　mixture　on　knock,　a　strategy　for　cooperative　control　of　λ　and　start　of　injection　(SOI)　is　proposed　in　Part　2,　which　can　lower　λ　to　1.4　within　the　allowable　borderline　knocking.　However,　this　strategy　fails　at　70°CA　BTDC　SOI.　Based　on　the　above　results,　a　strategy　to　synergistically　adjust　λ　and　intake　variable　valve　timing　is　adopted　in　Part　3,　which　suppresses　knock　mainly　by　varying　the　airflow　exchange　process　and　effective　compression　ratio.　Finally,　the　strategies　presented　in　Part　2　and　Part　3　allow　the　engine　to　control　the　KI　to　less　than　0.5　bar　at　WOT　and　stoichiometric　conditions,　which　ensures　power　performance.　©　2023　Elsevier　Ltd