Currently,　microplastic　pollution　poses　a　great　threat　to　diverse　ecosystems.　Microplastics　can　potentially　change　soil　characteristics　and　impact　soil　microorganisms,　and　then　affect　the　production　of　CO2,　CH4　and　other　greenhouse　gases.　However,　experimental　study　on　different　ecological　soils　is　lacking.　Herein,　we　experimentally　analyzed　the　CO2　and　CH4　production　potential　affected　by　four　types　of　microplastics　in　freshwater　(Poyang　Lake　in　Jiangxi　province,　paddy　soil　in　Hunan　province)　and　saltwater　(Salt　marsh　in　Shandong　province,　mangrove　soil　in　Fujian　province)　ecosystems.　Microplastics　promoted　CO2　production,　of　which　polyethylene　terephthalate　(PET)　had　the　greatest　impact.　In　our　study,　the　microplastics　that　had　the　greatest　impact　on　CH4　concentration　emissions　were　high-density　polyethylene　(1276　umol·g−1·L−1),　followed　by　polyvinyl　chloride　(384　umol·g−1·L−1),　polyethylene　terephthalate　(198　umol·g−1·L−1),　and　polyamide　(134　umol·g−1·L−1).　In　addition,　the　largest　impact　on　CO2　concentration　emissions　was　displayed　by　polyethylene　terephthalate　(2253　umol·g−1·L−1),　followed　by　polyvinyl　chloride　(2194　umol·g−1·L−1),　polyamide　(2006　umol·g−1·L−1),　and　high-density　polyethylene　(1522　umol·g−1·L−1).　However,　the　analysis　results　based　on　one-way　ANOVA　showed　that　CO2　emission　was　most　significantly　affected　by　soil　properties　rather　than　microplastics　types.　In　comparison,　the　influencing　factor　on　CH4　production　changed　from　soil　types　to　the　interaction　between　soil　types　and　microplastics,　and　finally　to　the　microplastics　with　the　increase　in　incubation　time.　Further,　by　comparing　CO2　and　CH4　production　and　Global　Warming　Equivalent　(GWE)　affected　by　microplastics,　freshwater　ecosystems　were　more　sensitive　than　saltwater.　For　all　the　soil　types　used　in　this　study,　high-density　polyethylene　had　the　greatest　impact　on　CH4　production　potential.　In　conclusion,　our　study　provided　basic　data　for　further　understanding　the　effects　of　microplastics　on　soil　greenhouse　gas　emissions　from　different　sources.　©　2022　by　the　authors.