A　high-speed　data　acquisition　system　for　multi-cylinder　spark　ignition　engine　was　developed　in　order　to　measure　the　indicator　diagrams　of　each　cylinder　simultaneously　with　the　maximum　sampling　frequency　of　1　MHz　and　the　total　input　signals　of　16　channels　at　the　same　time.　A　carburetor　S.I.　engine　reconstructed　into　a　double　fuel　engine　has　been　tested　using　the　data　acquisition　system　in　this　research.　At　lease　50　cycles＇　pressure　data　of　each　cylinder　were　measured.　The　average　value　and　the　fluctuant　coefficient　of　maximum　pressure　were　calculated.　The　comparison　among　different　cylinder＇s　inlet　air　quantity　has　been　made　using　the　maximum　pressure＇s　average　value.　Then　the　combustion　pressures　of　each　cylinder　have　been　measured　continuously　and　simultaneously　on　condition　that　either　burning　gasoline　or　compressed　natural　gas　(CNG).　The　comparison　of　combustion　and　variation　among　each　cylinder　has　been　made　using　the　averaged　value　and　the　variation　coefficient　of　the　maximum　combustion　pressure.　The　experiment　results　show　that　the　variation　coefficient　of　the　maximum　combustion　pressure　when　burning　CNG　is　lower　than　the　value　of　gasoline　engine.