Biodegradable　plastics,　as　an　alternative　to　petroleum　plastics,　are　fiercely　increasing,　but　their　incomplete　degradation　under　natural　conditions　may　lead　to　the　breakdown　into　microplastics　(MPs).　Here,　we　explored　the　impacts　of　chicken　manure-derived　(MBC)　and　wood　waste-derived　biochar　(WBC)　on　the　degradation　of　polylactic　acid　microplastics　(PLA-MPs)　during　soil　incubation　for　one　year.　Both　biochars　induced　more　pronounced　degradation　characteristics　in　PLA-MPs,　including　enhanced　surface　roughness,　the　proportion　of　MPs　＜　100　µm　by　12.89　%−25.67　%,　oxygen　loading　and　O/C　ratio　to　71.74　%−75.87　%　and　1.70–1.76,　as　well　as　accelerated　carbon　loss　and　the　cleavage　of　ester　group　and　C-C　bond.　Also,　biochar　increased　soil　pH,　depleted　inorganic　nitrogen　and　available　phosphorus,　and　changed　enzymic　activity　in　PLA-MP-polluted　soils.　We　proposed　that　both　biochars　accelerated　the　PLA-MP　degradation　by　inducing　alkaline,　aminolysis/ammonolysis,　oxidative,　and　microbial　degradation.　Among　these,　MBC　induced　aminolysis/ammonolysis　by　NH4+　via　Fe2+-driven　NO3-/NO2-　reduction　and　microbial　nitrogen　fixation,　and　oxidative　degradation　by　radicals　generated　through　Fenton/Fenton-like　reaction.　WBC　caused　aminolysis/ammonolysis　and　oxidative　degradation　mainly　through　dissimilatory　nitrate　reduction　to　ammonium　and　surface　free　radicals　on　biochar.　These　findings　indicate　that　biochar　has　the　potential　to　accelerate　PLA-MP　degradation,　and　its　regulatory　mechanism　depends　on　the　type　of　biochar.　©　2024　Elsevier　B.V.