Eight　electrodes　were　equipped　in　the　one　cylinder　head　gasket　of　a　gasoline　engine,　and　the　cylinder　spark　plug　was　also　used　as　an　ion　current　probe.　The　similarities　and　differences　between　the　ion　current　signal　detected　by　the　spark　plug　and　those　detected　by　the　eight　electrodes　equipped　in　the　gasket　were　obtained,　and　the　averaged　appearing　time　of　ion　current　was　chosen　as　a　characteristic　parameter　to　establish　the　correlation　between　the　characteristic　parameters　of　ion　current　and　parameters　about　combustion　in　cylinder.　The　correlation　coefficient　between　the　averaged　appearing　time　of　ion　current　and　the　pressure　in　cylinder　at　different　operating　conditions　were　analyzed.　The　results　show　that　the　ion　current　detected　by　ion　probes　installed　in　cylinder　gasket　is　not　affected　by　ignition　noise.　The　interdependency　between　the　averaged　appearing　time　of　ion　current　detected　at　the　No.　3　to　No.　7　gasket　ion　sensors　and　the　maximum　pressure　is　larger　than　0.9　at　different　ignition　advance　angles,　different　air/fuel　ratios　and　different　engine　speeds;　this　indicates　that　the　information　about　flame　propagation　obtained　with　ion　current　is　closely　related　to　the　cylinder　pressure.　©,　2015,　Chinese　Society　for　Internal　Combustion　Engines.　All　right　reserved.