The　development　of　hybrid　technology　and　the　use　of　zero-carbon　fuels　are　effective　means　to　improve　energy　efficiency　and　reduce　carbon　emissions.　In　this　study,　the　Miller　cycle　spark　ignition　engine　was　used,　and　four　load　control　strategies　of　throttle,　ammonia-hydrogen　ratio,　air–fuel　ratio,　and　variable　valve　timing　were　used　to　conduct　experimental　research　on　the　ammonia-hydrogen　engine.　The　experimental　results　show　that　the　throttle　strategy　provides　the　widest　output　range,　and　the　BMEP　is　raised　from　a　minimum　of　1　bar　to　7.4　bar.　The　ammonia-hydrogen　mixing　ratio　strategy　is　suitable　for　cold　start　conditions,　fully　utilizing　the　good　combustion　characteristics　of　hydrogen,　and　at　the　same　time　reducing　the　amount　of　hydrogen　used　in　the　heat　engine　process　as　much　as　possible.　The　air–fuel　ratio　strategy　provides　the　highest　thermal　efficiency　with　a　maximum　BTE　approaching　40%.　It　satisfies　the　energy-saving　demand　under　the　single-point　working　condition　of　the　engine　in　the　series　mode.　The　variable　valve　timing　strategy　can　realize　switching　between　BMEP　between　3.5　bar　and　6.5　bar,　and　keep　BTE　above　33%.　The　valve　timing　strategy　can　not　only　provide　a　wider　load　adjustment　range　but　also　maintain　high　thermal　efficiency.　Finally,　combining　the　effects　of　the　four　control　strategies　and　the　typical　operating　modes　of　the　hybrid　system,　this　study　suggests　that　the　throttle　strategy　is　suitable　for　the　feed　mode,　the　VVT　strategy　is　suitable　for　the　parallel　mode,　the　ammonia-hydrogen　mixture　ratio　strategy　is　suitable　for　the　cold　start　condition,　and　the　air–fuel　ratio　control　is　suitable　for　the　series　mode.　©　2023　Elsevier　Ltd