This　paper　analyzed　low　emissions　on　a　hydrogen-fueled　spark　ignition　(SI)　engine　at　the　cold　start　period　under　rich　combustion　through　ignition　timing　(IT)　control.　Cold　start　characteristics　of　hydrogen-fueled　engine　were　investigated　experimentally.　The　study　was　performed　under　different　IT.　The　results　demonstrated　that　when　excess　air　ratio　(lambda)　was　0.7　and　IT　varied　from　25　degrees　CA　BTDC　to　10　degrees　CA　ATDC,　the　peak　cylinder　pressure　of　the　first　cycle　and　the　successful　start　time　(SST)　of　hydrogen　engine　first　increased　and　then　decreased　with　the　retard　of　IT.　At　15　degrees　CA　BTDC,　the　hydrogen　engine　gained　the　shortest　SST　and　the　highest　cylinder　pressure　in　the　first　cycle.　Flame　development　period　(CA0-10)　first　shortened　and　then　lengthened,　and　flame　propagation　period　(CA10-90)　prolonged　when　IT　gradually　retarded.　The　average　NOx　emissions　efficiently　reduced　by　90.2%,　HC　and　CO　emissions　caused　by　the　evaporated　lubricant　oil　reduced　individually　by　33.8%　and　19.7%　in　the　first　6　s　during　the　cold　start　process　with　the　retard　of　IT.　Especially　when　IT　delayed　from　25　degrees　CA　BTDC　to　15　degrees　CA　BTDC,　the　effect　of　IT　on　HC　emissions　was　significant.　(C)　2019　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.