As　a　biodegradable　polymeric　material,　the　polylactic　acid　(PLA)　has　broad　applications　resulting　from　its　various　advantages　and　unique　characteristics.　Nevertheless,　the　application　of　PLA　in　various　fields　is　greatly　limited　by　its　high　flammability.　Our　recent　effort　focuses　on　the　manipulation　of　benzyldimethylhexadecylammonium　chloride　(HDBAC)　modified　titanium　carbide　(Ti3C2Tx)　ultra-thin　nanosheets　which　are　then　used　to　improve　the　fire　safety　of　PLA　composites　filled　with　silicon　microencapsulated　ammonium　polyphosphate　(SiAPP).　The　flame　retardant　evaluation　showed　that　when　2.0　wt%　HDBAC　modified　Ti3C2Tx　(HDBAC-Ti3C2Tx)　and　13.0　wt%　SiAPP　were　added,　the　LOI　value　was　increased　to　33.3%,　and　the　UL-94　V-0　level　was　obtained,　besides　the　peak　heat　release　rate,　total　heat　release,　peak　smoke　production　rate　and　total　smoke　release　decreased　by　49.8%,　31.9%,　60.3%　and　52.7%,　respectively.　The　barrier　and　catalytic　effects　of　the　modified　Ti3C2Tx　nanosheets　together　with　the　subsequently　formed　TiO2　and　phosphorus-containing　species　forming　intact　expanded　carbon　layers　and　interrupting　the　combustion　route　are　responsible　for　remarkably　improving　flame　retardancy　and　suppressing　toxic　gases　of　PLA.　This　work　provides　a　new　approach　for　greatly　reducing　the　fire　hazard　of　PLA.