Hydrogen　two-stage　direct-injection　enrichment　is　a　novel　injection　strategy　to　utilize　hydrogen　more　efficiently　and　effectively　in　gasoline　rotary　engines　by　inheriting　the　merits　of　hydrogen　and　direct　injection　simultaneously,　such　as　flexible　control,　efficiency　improvement,　and　emissions　reduction.　Based　on　the　CONVERGE　code　with　detailed　chemistry　solvers,　a　full-cycle　CFD　modeling　including　hydrogen　jet-flow　and　combustion　processes　was　presented　and　validated　by　experimental　data.　To　understand　the　role　of　hydrogen　two-stage　injection　in　improving　engine　performance　at　part-load　and　lean-burn　regime,　six　different　injection　arrangements　for　which　two-stage　injection　strategies　with　variable　hydrogen　amount　for　each　pulse　(up　to　30%　for　postinjection)　had　considered.　The　different　effects　on　species　evolution,　combustion　characteristics,　knock　propensity,　and　emissions　formation　were　analyzed　step-by-step.　The　simulation　results　showed　that　compared　with　direct-injected　hydrogen　for　single-pulse,　injecting　adequate　hydrogen　in　the　second　pulse　after　spark-ignition　onwards　performed　a　significant　beneficial　effect　on　the　mixture　stratification　and　flame　propagation,　especially　for　the　trailing　part　of　the　rotor　chamber,　which　contributed　to　the　improvement　in　both　combustion　characteristics　and　thermal　efficiency.　The　assessment　of　knock　propensity　demonstrated　that　the　two-stage　direct-injected　hydrogen　had　the　potential　of　mitigating　the　knock　under　lean　operations.　Using　split　injection　accompanied　by　an　optimized　hydrogen　allocation　strategy　allowed　substantial　unburned　hydrocarbon　and　carbon　monoxide　reductions　with　a　slight　nitrogen　oxide　penalty　rate　due　to　the　elevated　combustion　temperature.