A　time-domain　model　suitable　for　the　study　on　the　density　wave　instability　of　supercritical　water　in　multiple　parallel　channel　system　(the　number　of　channels　is　more　than　2)　was　established.　The　present　model　developed　an　iterative　solution　to　solve　the　coupling　among　parallel　channels.　Then　the　program　was　verified　by　the　experimental　data　obtained　in　open　literature.　After　that,　the　model　was　used　to　study　the　effect　of　system　pressure　(23-28　MPa),　inlet　fluid　temperature　(240-350　°C),　and　adding　perturbation　in　different　channels　on　the　density　wave　instability　of　supercritical　water　in　multiple　parallel　channel　system.　It　was　found　that　when　the　same　perturbation　was　added　on　some　of　channels　at　the　initial　time　(the　other　working　conditions　were　kept　unchanged),　the　number　of　perturbation　channels　had　almost　no　effect　on　the　oscillation　period　and　the　system　stability.　The　stability　of　the　multiple　channel　system　increased　with　the　increasing　in　system　pressure.　It　was　also　found　that　a　critical　value　about　the　inlet　fluid　temperature,　denoted　by　Tin-cr,　existed,　and　when　the　inlet　fluid　temperature　was　lower　than　the　critical　value　Tin-cr,　the　stability　of　the　multiple　channel　system　dropped　with　the　increase　of　inlet　fluid　temperature,　and　that　was　improved　when　inlet　fluid　temperature　was　higher　than　Tin-cr.　The　critical　value　Tin-cr　increased　gradually　with　the　increasing　in　the　amount　of　parallel　channels.　Moreover,　Tin-cr　was　lower　than　and　near　the　pseudo-critical　temperature　of　supercritical　water,　and　almost　had　no　changes　with　varying　system　pressure.　©　2016　Association　for　Computing　Machinery　Inc.　All　Rights　Reserved.