The　influence　of　ignition　timing　on　coefficient　of　variation　of　indicate　mean　effective　pressure　(CoVIMEP)　was　investigated.　The　influence　of　different　factors　on　cyclic　variations　is　compared　with　fixed　ignition　timing　and　minimum　CoVIMEP　(MCV)　ignition　timing.　Experimental　results　show　that　a　certain　ignition　timing　could　be　found　where　CoVIMEP　is　the　minimal　under　the　given　operation　condition.　Under　fixed　ignition　timing　conditions,　different　ignition　timings　will　give　different　cyclic　variations　characteristics.　Cyclic　variations　characteristics　are　unique　by　using　MCV　ignition　timing.