The　gas-hydrate-sediment-water　multiphase　flow　is　often　involved　in　drilling　and　exploitation　of　natural　gas　hydrate　(NGH)　reservoirs　in　seabed　due　to　its　weak　cementation;　therefore,　understanding　hydrate　formation　and　decomposition　in　sediment-contained　slurries　is　important.　In　this　work,　CH4　hydrate　formation　and　decomposition　in　clay-silt　slurries　was　explored,　the　effects　of　clay　type　and　content,　stirring　rate,　additives,　experimental　temperature,　and　pressure　were　systematically　investigated.　The　presence　of　clay　notably　accelerated　CH4　hydrate　formation　in　slurries,　and　the　montmorillonite　exhibited　a　more　obvious　promotion　effect　than　kaolinite.　As　the　stirring　rate　increased,　the　induction　time　and　reaction　time　were　shortened,　while　the　gas　consumption　rate　and　water　conversion　increased.　The　addition　of　500　ppm　sodium　dodecyl　sulfate　(SDS)　and　1.0　wt　%　fulvic　acid　(FA)　significantly　reduced　the　induction　time　and　increased　hydrate　formation　rate.　During　the　interaction　of　SDS　and　sediment,　CH4　hydrate　formed　in　the　slurries　instantaneously.　The　CH4　hydrate　decomposition　rate　in　slurries　increased　as　the　experimental　temperature　increased　or　the　pressure　decreased.　The　temperature　had　a　limited　impact　on　the　decomposition　time　above　freezing　point,　while　it　was　significant　below　freezing　point.　The　presence　of　clay　notably　decreased　the　CH4　hydrate　decomposition　rate　in　slurries.　Compared　to　the　clay-free　system,　the　Delta　T　d　values　(temperature　decreased　during　hydrate　decomposition)　in　the　montmorillonite　systems　were　decreased,　while　they　were　increased　in　the　kaolinite　systems.　The　findings　provide　valuable　insights　for　the　exploitation　of　marine　NGH.