Supercritical　water　gasification　technology　can　realize　efficient　conversion　of　biomass,　coal　and　other　organics　into　hydrogen　rich　gas.　But　the　efficiency　of　non-catalytic　gasification　at　relative　low　temperature　is　not　high.　Besides,　as　for　catalytic　gasification,　catalysis　mechanism　is　complex.　Thus　how　to　improve　efficiency　and　master　the　catalysis　mechanism　is　a　challenging　issue.　In　this　thesis,　supercritical　water　gasification　of　depolymerizing　slag　experiments　with　the　catalysis　of　different　kinds　of　catalysts　are　conducted　and　the　catalysis　mechanism　is　analyzed.　The　results　indicate　that　catalyst　mechanism　of　K2CO3　is　that　it　can　promote　the　swelling　and　hydrolysis　of　lignocellulose　and　increase　the　amounts　of　phenolic　intermediates.　Ru/Al2O3　presents　some　different　catalytic　properties.　It　facilitates　hydrogenation　reaction　of　hydrolysis　products,　ring-opening　reaction　and　the　cleavage　of　carbon-carbon　bonds　then　enhances　gasification　degree　and　increases　gasification　efficiency.　Moreover,　the　binary　catalyst　displays　a　good　synergic　effect　and　the　catalytic　activity　is　higher　than　that　of　any　single　catalyst　since　these　two　catalysts　promote　various　gasification　stages.　The　gasification　efficiency　and　hydrogen　yield　increase　13.22　mmol　g−1　and　66.46%　respectively　with　the　synergic　catalyst　of　K2CO3　and　Ru/Al2O3.　©　2020　Hydrogen　Energy　Publications　LLC