Optimizing　and　controlling　ignition　timing　is　one　of　the　important　technologies　to　improve　the　cold　start　performance　of　hydrogen　internal　combustion　engine.　The　combustion　and　performance　of　a　hydrogen　engine　during　cold　start　were　investigated　at　different　spark　timing　conditions.　An　electronically　controlled　hydrogen　port-injection　system　was　added　to　a　four-cylinder　commercial　gasoline　SI　engine,　and　a　new　electronic　control　unit　(NECU)　was　developed　to　realize　the　control　of　the　spark　timing.　During　the　experiment,　the　lubricant　and　coolant　temperatures　were　roughly　kept　at　(24±0.5)　℃,　and　the　spark　timing　was　varied　from　25°　BTDC　to　10°　ATDC.　Results　show　that　when　the　excess　air　ratio　is　0.7,　the　peak　cylinder　pressure　of　the　first　cycle　and　the　successful　start　duration　for　hydrogen　engine　first　increase　and　then　decrease　with　the　retarding　of　spark　timing.　At　the　spark　timing　of　15°　BTDC,　the　hydrogen　engine　gains　the　fastest　successful　start　and　the　highest　first　cycle　cylinder　pressure.　Flame　development　period　is　first　shortened　and　then　prolonged　and　flame　propagation　period　is　prolonged　gradually　with　the　retard　of　spark　timing.　The　average　emissions　of　NOx,　HC　and　CO　are　reduced　by　84.9%,　33.6%　and　23.8%,　respectively,　in　the　first　6　seconds　during　the　cold　start　process.　©　2019,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.