The　favorable　physicochemical　characteristics　of　hydrogen　make　it　an　excellent　alternative　fuel　for　IC　engines.　Compared　with　hydrogen　port　injection,　hydrogen　direct　injection　provides　multiple　degrees　of　freedom　for　injection　strategies　and　mixture　formation,　which　can　effectively　suppress　abnormal　combustion　and　enhance　engine　performance.　Variable　valve　timing　(VVT)　and　the　Miller　cycle,　as　advanced　and　effective　means　of　improving　engine　performance,　are　less　investigated　based　on　a　direct-injection　(DI)　hydrogen　engine.　Hence,　to　optimize　the　performance　of　a　DI　hydrogen　engine,　strategies　of　the　Miller　cycle　and　VVT　are　introduced.　In　this　work,　a　1.5　L　direct-injection　engine　with　a　VVT　system　was　employed　to　evaluate　the　effects　of　the　Miller　cycle,　intake　valve　closing　(IVC)　timing,　and　exhaust　valve　opening　(EVO)　timing　on　the　airflow　exchange　process,　incylinder　charge　characteristics,　heat　release　process,　dynamics　and　emission　characteristics.　The　engine　speed　was　stabilized　at　1400　rpm　and　the　strategies　of　lean　combustion　and　late　injection　were　used.　The　main　results　are　as　follows.　As　the　IVC　timing　is　delayed,　the　ratio　of　pumping　mean　effective　pressure　to　indicated　mean　effective　pressure　(PMEP/IMEP)　first　decreases　and　then　slightly　increases,　and　the　engine　tends　to　achieve　a　high　level　of　brake　thermal　efficiency　(BTE)　when　PMEP/IMEP　is　lower.　The　optimization　of　intake　and　exhaust　VVT　can　shorten　combustion　duration　and　reduce　cyclic　variation　by　increasing　volumetric　efficiency　and　improving　mixture　distribution　at　ignition　timing.　Furthermore,　the　engine　reaches　42.22%　BTE　and　a　high　level　of　brake　mean　effective　pressure　by　the　cooperative　control　of　IVC　and　EVO　timing.　NOx　emissions　can　be　controlled　below　100　ppm　by　employing　the　synergistic　effect　of　the　Miller　cycle　and　VVT.　It　is　worth　mentioning　that　exhaust　VVT　as　a　way　to　compensate　for　the　performance　of　the　DI　hydrogen　engine　with　the　Miller　cycle　should　not　be　ignored.