The　evaluation　of　inter-provincial　carbon　emission　efficiency　and　the　analysis　of　its　influencing　factors　hold　great　practical　significance　for　reducing　carbon　emissions　and　promoting　sustainable　development　in　ecological　management.　To　address　the　shortcomings　of　existing　research　in　the　classification　evaluation　of　carbon　emission　efficiency　and　account　for　the　impacts　of　different　environmental　regulatory　policies　on　carbon　emissions,　this　paper　aims　to　examine　the　impact　of　formal　and　informal　environmental　regulations　on　carbon　emission　efficiency.　This　is　accomplished　by　utilizing　a　combination　of　the　data　envelopment　analysis　(DEA)　model,　entropy　weighting,　and　k-means　cluster　analysis　methods.　The　fixed-effects　model　is　also　applied　to　examine　the　influences　of　different　factors　on　carbon　emission　efficiency　under　different　categories.　To　conduct　the　case　studies,　carbon　emission　management　data　from　30　provinces　in　China　are　collected,　and　the　results　show　the　following:　(1)　Formal　environmental　regulations　exhibit　a　“U-shaped”　relationship　with　carbon　emission　efficiency,　whereas　informal　environmental　regulations　have　an　“inverted　U-shaped”　relationship　with　carbon　emission　efficiency.　(2)　Under　the　cluster　analysis　of　carbon　emission　efficiency,　formal　environmental　regulations　are　found　to　have　a　stronger　incentive　effect　on　inter-provincial　carbon　efficiency　compared　to　informal　environmental　regulations.　This　study　carries　significant　theoretical　and　practical　implications　for　China’s　timely　attainment　of　its　double-carbon　target.　©　2023　by　the　authors.